#
#   Symbol Table
#


import re
import copy
import operator
import math

from ..Utils import try_finally_contextmanager
from .Errors import warning, error, InternalError, performance_hint
from .StringEncoding import EncodedString
from . import Options, Naming
from . import PyrexTypes
from .PyrexTypes import py_object_type, unspecified_type
from .TypeSlots import (
    pyfunction_signature, pymethod_signature, richcmp_special_methods,
    get_slot_table, get_property_accessor_signature)
from . import DebugFlags

from . import Code


def c_safe_identifier(cname):
    # There are some C limitations on struct entry names.
    if ((cname[:2] == '__' and not (cname.startswith(Naming.pyrex_prefix)
                                    or cname in ('__weakref__', '__dict__')))
            or cname in Naming.reserved_cnames):
        cname = Naming.pyrex_prefix + cname
    return cname


def punycodify_name(cname, mangle_with=None):
    # if passed the mangle_with should be a byte string
    # modified from  PEP489
    if cname.isascii():
        return cname

    cname = cname.encode('punycode').replace(b'-', b'_').decode('ascii')
    if mangle_with:
        # sometimes it necessary to mangle unicode names alone where
        # they'll be inserted directly into C, because the punycode
        # transformation can turn them into invalid identifiers
        cname = "%s_%s" % (mangle_with, cname)
    elif cname.startswith(Naming.pyrex_prefix):
        # a punycode name could also be a valid ascii variable name so
        # change the prefix to distinguish
        cname = cname.replace(Naming.pyrex_prefix,
                              Naming.pyunicode_identifier_prefix, 1)

    return cname


class BufferAux:
    writable_needed = False

    def __init__(self, buflocal_nd_var, rcbuf_var):
        self.buflocal_nd_var = buflocal_nd_var
        self.rcbuf_var = rcbuf_var

    def __repr__(self):
        return "<BufferAux %r>" % self.__dict__


class Entry:
    # A symbol table entry in a Scope or ModuleNamespace.
    #
    # name             string     Python name of entity
    # cname            string     C name of entity
    # type             PyrexType  Type of entity
    # doc              string     Doc string
    # annotation       ExprNode   PEP 484/526 annotation
    # init             string     Initial value
    # visibility       'private' or 'public' or 'extern'
    # is_builtin       boolean    Is an entry in the Python builtins dict
    # is_cglobal       boolean    Is a C global variable
    # is_pyglobal      boolean    Is a Python module-level variable
    #                               or class attribute during
    #                               class construction
    # is_member        boolean    Is an assigned class member
    # is_pyclass_attr  boolean    Is a name in a Python class namespace
    # is_variable      boolean    Is a variable
    # is_cfunction     boolean    Is a C function
    # is_cmethod       boolean    Is a C method of an extension type
    # is_builtin_cmethod boolean  Is a C method of a builtin type (implies is_cmethod)
    # is_unbound_cmethod boolean  Is an unbound C method of an extension type
    # is_final_cmethod   boolean  Is non-overridable C method
    # is_inline_cmethod  boolean  Is inlined C method
    # is_anonymous     boolean    Is a anonymous pyfunction entry
    # is_type          boolean    Is a type definition
    # is_cclass        boolean    Is an extension class
    # is_cclass_var_rentry  boolean Is a var entry of an extension type
    #                              (Hack! Only needed because most C globals are
    #                               static variables while these live in the module scope.
    #                               Remove when fixed.)
    # is_cpp_class     boolean    Is a C++ class
    # is_const         boolean    Is a constant
    # is_property      boolean    Is a property of an extension type:
    # doc_cname        string or None  C const holding the docstring
    # getter_cname     string          C func for getting property
    # setter_cname     string          C func for setting or deleting property
    # is_cproperty     boolean         Is an inline property of an external type
    # is_self_arg      boolean    Is the "self" arg of an exttype method
    # is_arg           boolean    Is the arg of a method
    # is_local         boolean    Is a local variable
    # in_closure       boolean    Is referenced in an inner scope
    # in_subscope      boolean    Belongs to a generator expression scope
    # is_readonly      boolean    Can't be assigned to
    # func_cname       string     C func implementing Python func
    # wrapperbase_cname [string]  C wrapperbase object name
    # func_modifiers   [string]   C function modifiers ('inline')
    # pos              position   Source position where declared
    # namespace_cname  string     If is_pyglobal, the C variable
    #                               holding its home namespace
    # pymethdef_cname  string     PyMethodDef structure
    # signature        Signature  Arg & return types for Python func
    # as_variable      Entry      Alternative interpretation of extension
    #                               type name or builtin C function as a variable
    # xdecref_cleanup  boolean    Use Py_XDECREF for error cleanup
    # in_cinclude      boolean    Suppress C declaration code
    # enum_values      [Entry]    For enum types, list of values
    # qualified_name   string     "modname.funcname" or "modname.classname"
    #                               or "modname.classname.funcname"
    # is_declared_generic  boolean  Is declared as PyObject * even though its
    #                                 type is an extension type
    # as_module        None       Module scope, if a cimported module
    # is_inherited     boolean    Is an inherited attribute of an extension type
    # pystring_cname   string     C name of Python version of string literal
    # is_interned      boolean    For string const entries, value is interned
    # is_identifier    boolean    For string const entries, value is an identifier
    # used             boolean
    # is_special       boolean    Is a special method or property accessor
    #                               of an extension type
    # defined_in_pxd   boolean    Is defined in a .pxd file (not just declared)
    # api              boolean    Generate C API for C class or function
    # utility_code     string     Utility code needed when this entry is used
    #
    # buffer_aux       BufferAux or None  Extra information needed for buffer variables
    # inline_func_in_pxd boolean  Hacky special case for inline function in pxd file.
    #                             Ideally this should not be necessary.
    # might_overflow   boolean    In an arithmetic expression that could cause
    #                             overflow (used for type inference).
    # utility_code_definition     For some Cython builtins, the utility code
    #                             which contains the definition of the entry.
    #                             Currently only supported for CythonScope entries.
    # error_on_uninitialized      Have Control Flow issue an error when this entry is
    #                             used uninitialized
    # cf_used          boolean    Entry is used
    # is_fused_specialized boolean Whether this entry of a cdef or def function
    #                              is a specialization
    # is_cgetter       boolean    Is a c-level getter function
    # is_cpp_optional  boolean    Entry should be declared as std::optional (cpp_locals directive)
    # known_standard_library_import     Either None (default), an empty string (definitely can't be determined)
    #                             or a string of "modulename.something.attribute"
    #                             Used for identifying imports from typing/dataclasses etc
    # pytyping_modifiers          Python type modifiers like "typing.ClassVar" but also "dataclasses.InitVar"
    # enum_int_value  None or int  If known, the int that corresponds to this enum value
    # specialiser  function or None  Callable to specialise a function to specific C arguments.

    # TODO: utility_code and utility_code_definition serves the same purpose...

    inline_func_in_pxd = False
    borrowed = 0
    init = ""
    annotation = None
    visibility = 'private'
    is_builtin = 0
    is_cglobal = 0
    is_pyglobal = 0
    is_member = 0
    is_pyclass_attr = 0
    is_variable = 0
    is_cfunction = 0
    is_cmethod = 0
    is_builtin_cmethod = False
    is_unbound_cmethod = 0
    is_final_cmethod = 0
    is_inline_cmethod = 0
    is_anonymous = 0
    is_type = 0
    is_cclass = 0
    is_cclass_var_entry = False  # Remove when other cglobals are in the module scope
    is_cpp_class = 0
    is_const = 0
    is_property = 0
    is_cproperty = 0
    doc_cname = None
    getter_cname = None
    setter_cname = None
    is_self_arg = 0
    is_arg = 0
    is_local = 0
    in_closure = 0
    from_closure = 0
    in_subscope = 0
    is_declared_generic = 0
    is_readonly = 0
    pyfunc_cname = None
    func_cname = None
    func_modifiers = []
    final_func_cname = None
    doc = None
    as_variable = None
    xdecref_cleanup = 0
    in_cinclude = 0
    as_module = None
    is_inherited = 0
    pystring_cname = None
    is_identifier = 0
    is_interned = 0
    used = 0
    is_special = 0
    defined_in_pxd = 0
    is_implemented = 0
    api = 0
    utility_code = None
    specialiser = None
    is_overridable = 0
    buffer_aux = None
    prev_entry = None
    might_overflow = 0
    fused_cfunction = None
    is_fused_specialized = False
    utility_code_definition = None
    needs_property = False
    in_with_gil_block = 0
    from_cython_utility_code = None
    error_on_uninitialized = False
    cf_used = True
    outer_entry = None
    is_cgetter = False
    is_cpp_optional = False
    known_standard_library_import = None
    pytyping_modifiers = None
    enum_int_value = None
    vtable_type = None

    def __init__(self, name, cname, type, pos = None, init = None):
        self.name = name
        self.cname = cname
        self.type = type
        self.pos = pos
        self.init = init
        self.overloaded_alternatives = []
        self.cf_assignments = []
        self.cf_references = []
        self.inner_entries = []
        self.defining_entry = self

    # Debug helper to find places where entry types are assigned.
    if DebugFlags.debug_verbose_entry_types:
        @property
        def type(self):
            return self.__dict__['type']

        @type.setter
        def type(self, new_type):
            print(f"ENTRY {self.name}[{self.cname}] TYPE: {self.__dict__.get('type')} -> {new_type}")
            self.__dict__['type'] = new_type

    def __repr__(self):
        return "%s(<%x>, name=%s, type=%s)" % (type(self).__name__, id(self), self.name, self.type)

    def already_declared_here(self):
        error(self.pos, "Previous declaration is here")

    def redeclared(self, pos):
        error(pos, "'%s' does not match previous declaration" % self.name)
        self.already_declared_here()

    def all_alternatives(self):
        return [self] + self.overloaded_alternatives

    def best_function_match(self, scope, arg_types, fail_if_empty=False, arg_is_lvalue_array=None):
        func_entry = None
        if self.specialiser is not None:
            func_entry = self.specialiser(scope, arg_types)
        if func_entry is None:
            if self.type.is_fused:
                functypes = self.type.get_all_specialized_function_types()
                alternatives = [f.entry for f in functypes]
            else:
                alternatives = self.all_alternatives()
            func_entry = PyrexTypes.best_match(
                arg_types, alternatives, fail_if_empty=fail_if_empty, arg_is_lvalue_array=arg_is_lvalue_array)
        return func_entry

    def all_entries(self):
        return [self] + self.inner_entries

    def __lt__(left, right):
        if isinstance(left, Entry) and isinstance(right, Entry):
            return (left.name, left.cname) < (right.name, right.cname)
        else:
            return NotImplemented

    @property
    def cf_is_reassigned(self):
        return len(self.cf_assignments) > 1

    def make_cpp_optional(self):
        assert self.type.is_cpp_class
        self.is_cpp_optional = True
        assert not self.utility_code  # we're not overwriting anything?
        self.utility_code_definition = Code.UtilityCode.load_cached("OptionalLocals", "CppSupport.cpp")

    def declared_with_pytyping_modifier(self, modifier_name):
        return modifier_name in self.pytyping_modifiers if self.pytyping_modifiers else False


class InnerEntry(Entry):
    """
    An entry in a closure scope that represents the real outer Entry.
    """
    from_closure = True

    def __init__(self, outer_entry, scope):
        Entry.__init__(self, outer_entry.name,
                       outer_entry.cname,
                       outer_entry.type,
                       outer_entry.pos)
        self.outer_entry = outer_entry
        self.scope = scope

        # share state with (outermost) defining entry
        outermost_entry = outer_entry
        while outermost_entry.outer_entry:
            outermost_entry = outermost_entry.outer_entry
        self.defining_entry = outermost_entry
        self.inner_entries = outermost_entry.inner_entries
        self.cf_assignments = outermost_entry.cf_assignments
        self.cf_references = outermost_entry.cf_references
        self.overloaded_alternatives = outermost_entry.overloaded_alternatives
        self.is_cpp_optional = outermost_entry.is_cpp_optional
        self.inner_entries.append(self)

    def __getattr__(self, name):
        if name.startswith('__'):
            # we wouldn't have been called if it was there
            raise AttributeError(name)
        return getattr(self.defining_entry, name)

    def all_entries(self):
        return self.defining_entry.all_entries()


class Scope:
    # name              string             Unqualified name
    # outer_scope       Scope or None      Enclosing scope
    # entries           {string : Entry}   Python name to entry, non-types
    # const_entries     [Entry]            Constant entries
    # type_entries      [Entry]            Struct/union/enum/typedef/exttype entries
    # sue_entries       [Entry]            Struct/union/enum entries
    # arg_entries       [Entry]            Function argument entries
    # var_entries       [Entry]            User-defined variable entries
    # pyfunc_entries    [Entry]            Python function entries
    # cfunc_entries     [Entry]            C function entries
    # c_class_entries   [Entry]            All extension type entries
    # cname_to_entry    {string : Entry}   Temp cname to entry mapping
    # return_type       PyrexType or None  Return type of function owning scope
    # is_builtin_scope  boolean            Is the builtin scope of Python/Cython
    # is_py_class_scope boolean            Is a Python class scope
    # is_c_class_scope  boolean            Is an extension type scope
    # is_local_scope    boolean            Is a local (i.e. function/method/generator) scope
    # is_closure_scope  boolean            Is a closure scope
    # is_generator_expression_scope boolean   A subset of closure scope used for generator expressions
    # is_passthrough    boolean            Outer scope is passed directly
    # is_cpp_class_scope  boolean          Is a C++ class scope
    # is_property_scope boolean            Is a extension type property scope
    # is_c_dataclass_scope     boolean or "frozen"  is a cython.dataclasses.dataclass
    # scope_prefix      string             Disambiguator for C names
    # in_cinclude       boolean            Suppress C declaration code
    # qualified_name    string             "modname" or "modname.classname"
    #                                        Python strings in this scope
    # nogil             boolean            In a nogil section
    # directives        dict               Helper variable for the recursive
    #                                      analysis, contains directive values.
    # is_internal       boolean            Is only used internally (simpler setup)
    # scope_predefined_names  list of str   Class variable containing special names defined by
    #                                      this type of scope (e.g. __builtins__, __qualname__)
    # node_positions_to_offset  {pos: offset}  Mapping from node positions to line table offsets

    is_builtin_scope = 0
    is_py_class_scope = 0
    is_c_class_scope = 0
    is_closure_scope = 0
    is_local_scope = False
    is_generator_expression_scope = 0
    is_comprehension_scope = 0
    is_passthrough = 0
    is_cpp_class_scope = 0
    is_property_scope = 0
    is_module_scope = 0
    is_c_dataclass_scope = False
    is_internal = 0
    scope_prefix = ""
    in_cinclude = 0
    nogil = 0
    fused_to_specific = None
    return_type = None
    scope_predefined_names = []
    # Do ambiguous type names like 'int' and 'float' refer to the C types? (Otherwise, Python types.)
    in_c_type_context = True
    node_positions_to_offset = {}  # read-only fallback dict

    def __init__(self, name, outer_scope, parent_scope):
        # The outer_scope is the next scope in the lookup chain.
        # The parent_scope is used to derive the qualified name of this scope.
        self.name = name
        self.outer_scope = outer_scope
        self.parent_scope = parent_scope
        mangled_name = "%d%s_" % (len(name), name.replace('.', '_dot_'))
        qual_scope = self.qualifying_scope()
        if qual_scope:
            self.qualified_name = qual_scope.qualify_name(name)
            self.scope_prefix = qual_scope.scope_prefix + mangled_name
        else:
            self.qualified_name = EncodedString(name)
            self.scope_prefix = mangled_name
        self.entries = {}
        self.subscopes = set()
        self.const_entries = []
        self.type_entries = []
        self.sue_entries = []
        self.arg_entries = []
        self.var_entries = []
        self.pyfunc_entries = []
        self.cfunc_entries = []
        self.c_class_entries = []
        self.defined_c_classes = []
        self.imported_c_classes = {}
        self.cname_to_entry = {}
        self.identifier_to_entry = {}
        self.num_to_entry = {}
        self.obj_to_entry = {}
        self.buffer_entries = []
        self.lambda_defs = []
        self.id_counters = {}
        for var_name in self.scope_predefined_names:
            self.declare_var(EncodedString(var_name), py_object_type, pos=None)

    def __deepcopy__(self, memo):
        return self

    def merge_in(self, other, merge_unused=True, allowlist=None):
        # Use with care...
        entries = []
        for name, entry in other.entries.items():
            if not allowlist or name in allowlist:
                if entry.used or merge_unused:
                    entries.append((name, entry))

        self.entries.update(entries)

        for attr in ('const_entries',
                     'type_entries',
                     'sue_entries',
                     'arg_entries',
                     'var_entries',
                     'pyfunc_entries',
                     'cfunc_entries',
                     'c_class_entries'):
            self_entries = getattr(self, attr)
            names = {e.name for e in self_entries}
            for entry in getattr(other, attr):
                if (entry.used or merge_unused) and entry.name not in names:
                    self_entries.append(entry)

    def __str__(self):
        return "<%s %s>" % (self.__class__.__name__, self.qualified_name)

    def qualifying_scope(self):
        return self.parent_scope

    def mangle(self, prefix, name = None):
        if name:
            return punycodify_name("%s%s%s" % (prefix, self.scope_prefix, name))
        else:
            return self.parent_scope.mangle(prefix, self.name)

    def mangle_internal(self, name):
        # Mangle an internal name so as not to clash with any
        # user-defined name in this scope.
        prefix = "%s%s_" % (Naming.pyrex_prefix, name)
        return self.mangle(prefix)
        #return self.parent_scope.mangle(prefix, self.name)

    def mangle_class_private_name(self, name):
        if self.parent_scope:
            return self.parent_scope.mangle_class_private_name(name)
        return name

    def next_id(self, name=None):
        # Return a cname fragment that is unique for this module
        counters = self.global_scope().id_counters
        try:
            count = counters[name] + 1
        except KeyError:
            count = 0
        counters[name] = count
        if name:
            if not count:
                # unique names don't need a suffix, reoccurrences will get one
                return name
            return '%s%d' % (name, count)
        else:
            return '%d' % count

    @property
    def context(self):
        return self.global_scope().context

    def global_scope(self):
        """ Return the module-level scope containing this scope. """
        return self.outer_scope.global_scope()

    def builtin_scope(self):
        """ Return the module-level scope containing this scope. """
        return self.outer_scope.builtin_scope()

    def iter_local_scopes(self):
        yield self
        if self.subscopes:
            yield from sorted(self.subscopes, key=operator.attrgetter('scope_prefix'))

    @try_finally_contextmanager
    def new_c_type_context(self, in_c_type_context=None):
        old_c_type_context = self.in_c_type_context
        if in_c_type_context is not None:
            self.in_c_type_context = in_c_type_context
        yield
        self.in_c_type_context = old_c_type_context

    def handle_already_declared_name(self, name, cname, type, pos, visibility, copy_entry=False):
        """
        Returns an entry or None

        If it returns an entry, it makes sense for "declare" to keep using that
        entry and not to declare its own.

        May be overridden (e.g. for builtin scope,
        which always allows redeclarations)
        """
        entry = None
        entries = self.entries
        old_entry = entries[name]

        # Reject redeclared C++ functions only if they have a compatible type signature.
        cpp_override_allowed = False
        if type.is_cfunction and old_entry.type.is_cfunction and self.is_cpp():
            # If we redefine a C++ class method which is either inherited
            # or automatically generated (base constructor), then it's fine.
            # Otherwise, we shout.
            for alt_entry in old_entry.all_alternatives():
                if type.compatible_signature_with(alt_entry.type):
                    if name == '<init>' and not type.args:
                        # Cython pre-declares the no-args constructor - allow later user definitions.
                        cpp_override_allowed = True
                    elif alt_entry.is_inherited:
                        # Note that we can override an inherited method with a compatible but not exactly equal signature, as in C++.
                        cpp_override_allowed = True
                    if cpp_override_allowed:
                        entry = alt_entry
                        if copy_entry:
                            entry = copy.copy(alt_entry)

                        # A compatible signature doesn't mean the exact same signature,
                        # so we're taking the new signature for the entry.
                        entry.type = type
                        entry.is_inherited = False
                        # Updating the entry attributes which can be modified in the method redefinition.
                        entry.cname = cname
                        entry.pos = pos
                    break
            else:
                cpp_override_allowed = True

        if cpp_override_allowed:
            # C++ function/method overrides with different signatures are ok.
            pass
        elif entries[name].is_inherited:
            # Likewise ignore inherited classes.
            pass
        else:
            if visibility == 'extern':
                # Silenced outside of "cdef extern" blocks, until we have a safe way to
                # prevent pxd-defined cpdef functions from ending up here.
                warning(pos, "'%s' redeclared " % name, 1 if self.in_cinclude else 0)
            elif visibility != 'ignore':
                error(pos, "'%s' redeclared " % name)
                self.entries[name].already_declared_here()
            return None

        return entry


    def declare(self, name, cname, type, pos, visibility, shadow = 0, is_type = 0, create_wrapper = 0):
        # Create new entry, and add to dictionary if
        # name is not None. Reports a warning if already
        # declared.
        if type.is_buffer and not isinstance(self, LocalScope):  # and not is_type:
            error(pos, 'Buffer types only allowed as function local variables')
        if not self.in_cinclude and cname and re.match("^_[_A-Z]+$", cname):
            # See https://www.gnu.org/software/libc/manual/html_node/Reserved-Names.html#Reserved-Names
            warning(pos, "'%s' is a reserved name in C." % cname, -1)

        entries = self.entries
        entry = None
        if name and name in entries and not shadow:
            entry = self.handle_already_declared_name(name, cname, type, pos, visibility)

        if not entry:
            entry = Entry(name, cname, type, pos = pos)
            entry.in_cinclude = self.in_cinclude
            entry.create_wrapper = create_wrapper

            if name:
                entry.qualified_name = self.qualify_name(name)
                if not shadow:
                    if name in entries and self.is_cpp() and type.is_cfunction and not entries[name].is_cmethod:
                        # Which means: function or cppclass method is already present
                        entries[name].overloaded_alternatives.append(entry)
                    else:
                        entries[name] = entry

        if type.is_memoryviewslice:
            entry.init = type.default_value

        entry.scope = self
        entry.visibility = visibility
        return entry

    def qualify_name(self, name):
        return EncodedString("%s.%s" % (self.qualified_name, name))

    def declare_const(self, name, type, value, pos, cname = None, visibility = 'private', api = 0, create_wrapper = 0):
        # Add an entry for a named constant.
        if not cname:
            if self.in_cinclude or (visibility == 'public' or api):
                cname = name
            else:
                cname = self.mangle(Naming.enum_prefix, name)
        entry = self.declare(name, cname, type, pos, visibility, create_wrapper = create_wrapper)
        entry.is_const = 1
        entry.value_node = value
        return entry

    def declare_type(self, name, type, pos,
            cname = None, visibility = 'private', api = 0, defining = 1,
            shadow = 0, template = 0):
        # Add an entry for a type definition.
        if not cname:
            cname = name
        entry = self.declare(name, cname, type, pos, visibility, shadow,
                             is_type=True)
        entry.is_type = 1
        entry.api = api
        if defining:
            self.type_entries.append(entry)

        # don't replace an entry that's already set
        if not template and getattr(type, "entry", None) is None:
            type.entry = entry

        # here we would set as_variable to an object representing this type
        return entry

    def declare_typedef(self, name, base_type, pos, cname = None,
                        visibility = 'private', api = 0):
        if not cname:
            if self.in_cinclude or (visibility != 'private' or api):
                cname = name
            else:
                cname = self.mangle(Naming.type_prefix, name)
        try:
            if self.is_cpp_class_scope:
                namespace = self.outer_scope.lookup(self.name).type
            else:
                namespace = None
            type = PyrexTypes.create_typedef_type(name, base_type, cname,
                                                  (visibility == 'extern'),
                                                  namespace)
        except ValueError as e:
            error(pos, e.args[0])
            type = PyrexTypes.error_type
        entry = self.declare_type(name, type, pos, cname,
                                  visibility = visibility, api = api)
        type.qualified_name = entry.qualified_name
        return entry

    def declare_struct_or_union(self, name, kind, scope,
                                typedef_flag, pos, cname = None,
                                visibility = 'private', api = 0,
                                packed = False):
        # Add an entry for a struct or union definition.
        if not cname:
            if self.in_cinclude or (visibility == 'public' or api):
                cname = name
            else:
                cname = self.mangle(Naming.type_prefix, name)
        entry = self.lookup_here(name)
        if not entry:
            in_cpp = self.is_cpp()
            type = PyrexTypes.CStructOrUnionType(
                name, kind, scope, typedef_flag, cname, packed,
                in_cpp = in_cpp)
            entry = self.declare_type(name, type, pos, cname,
                visibility = visibility, api = api,
                defining = scope is not None)
            self.sue_entries.append(entry)
            type.entry = entry
        else:
            if not (entry.is_type and entry.type.is_struct_or_union
                    and entry.type.kind == kind):
                warning(pos, "'%s' redeclared  " % name, 0)
            elif scope and entry.type.scope:
                warning(pos, "'%s' already defined  (ignoring second definition)" % name, 0)
            else:
                self.check_previous_typedef_flag(entry, typedef_flag, pos)
                self.check_previous_visibility(entry, visibility, pos)
                if scope:
                    entry.type.scope = scope
                    self.type_entries.append(entry)
        if self.is_cpp_class_scope:
            entry.type.namespace = self.outer_scope.lookup(self.name).type
        return entry

    def declare_cpp_class(self, name, scope,
            pos, cname = None, base_classes = (),
            visibility = 'extern', templates = None):
        if cname is None:
            if self.in_cinclude or (visibility != 'private'):
                cname = name
            else:
                cname = self.mangle(Naming.type_prefix, name)
        base_classes = list(base_classes)
        entry = self.lookup_here(name)
        if not entry:
            type = PyrexTypes.CppClassType(
                name, scope, cname, base_classes, templates = templates)
            entry = self.declare_type(name, type, pos, cname,
                visibility = visibility, defining = scope is not None)
            self.sue_entries.append(entry)
        else:
            if not (entry.is_type and entry.type.is_cpp_class):
                error(pos, "'%s' redeclared " % name)
                entry.already_declared_here()
                return None
            elif scope and entry.type.scope:
                warning(pos, "'%s' already defined  (ignoring second definition)" % name, 0)
            else:
                if scope:
                    entry.type.scope = scope
                    self.type_entries.append(entry)
            if base_classes:
                if entry.type.base_classes and entry.type.base_classes != base_classes:
                    error(pos, "Base type does not match previous declaration")
                    entry.already_declared_here()
                else:
                    entry.type.base_classes = base_classes
            if templates or entry.type.templates:
                if templates != entry.type.templates:
                    error(pos, "Template parameters do not match previous declaration")
                    entry.already_declared_here()

        def declare_inherited_attributes(entry, base_classes):
            for base_class in base_classes:
                if base_class is PyrexTypes.error_type:
                    continue
                if base_class.scope is None:
                    error(pos, "Cannot inherit from incomplete type")
                else:
                    declare_inherited_attributes(entry, base_class.base_classes)
                    entry.type.scope.declare_inherited_cpp_attributes(base_class)
        if scope:
            declare_inherited_attributes(entry, base_classes)
            scope.declare_var(name="this", cname="this", type=PyrexTypes.CPtrType(entry.type), pos=entry.pos)
        if self.is_cpp_class_scope:
            entry.type.namespace = self.outer_scope.lookup(self.name).type
        return entry

    def check_previous_typedef_flag(self, entry, typedef_flag, pos):
        if typedef_flag != entry.type.typedef_flag:
            error(pos, "'%s' previously declared using '%s'" % (
                entry.name, ("cdef", "ctypedef")[entry.type.typedef_flag]))

    def check_previous_visibility(self, entry, visibility, pos):
        if entry.visibility != visibility:
            error(pos, "'%s' previously declared as '%s'" % (
                entry.name, entry.visibility))

    def declare_enum(self, name, pos, cname, scoped, typedef_flag,
            visibility='private', api=0, create_wrapper=0, doc=None):
        if name:
            if not cname:
                if (self.in_cinclude or visibility == 'public'
                        or visibility == 'extern' or api):
                    cname = name
                else:
                    cname = self.mangle(Naming.type_prefix, name)
            if self.is_cpp_class_scope:
                namespace = self.outer_scope.lookup(self.name).type
            else:
                namespace = None

            if scoped:
                type = PyrexTypes.CppScopedEnumType(name, cname, namespace, doc=doc)
            else:
                type = PyrexTypes.CEnumType(name, cname, typedef_flag, namespace, doc=doc)
        else:
            type = PyrexTypes.c_anon_enum_type
        entry = self.declare_type(name, type, pos, cname = cname,
            visibility = visibility, api = api)
        if scoped:
            entry.utility_code = Code.UtilityCode.load_cached("EnumClassDecl", "CppSupport.cpp")
            self.use_entry_utility_code(entry)
        entry.create_wrapper = create_wrapper
        entry.enum_values = []

        self.sue_entries.append(entry)
        return entry

    def declare_tuple_type(self, pos, components):
        return self.outer_scope.declare_tuple_type(pos, components)

    def declare_var(self, name, type, pos,
                    cname=None, visibility='private',
                    api=False, in_pxd=False, is_cdef=False, pytyping_modifiers=None):
        # Add an entry for a variable.
        if not cname:
            if visibility != 'private' or api:
                cname = name
            else:
                cname = self.mangle(Naming.var_prefix, name)
        entry = self.declare(name, cname, type, pos, visibility)
        entry.is_variable = 1
        if type.is_cpp_class and visibility != 'extern':
            if self.directives['cpp_locals']:
                entry.make_cpp_optional()
            else:
                type.check_nullary_constructor(pos)
        if in_pxd and visibility != 'extern':
            entry.defined_in_pxd = 1
            entry.used = 1
        if api:
            entry.api = 1
            entry.used = 1
        if pytyping_modifiers:
            entry.pytyping_modifiers = pytyping_modifiers
        return entry

    def _reject_pytyping_modifiers(self, pos, modifiers, allowed=()):
        if not modifiers:
            return
        for modifier in modifiers:
            if modifier not in allowed:
                error(pos, "Modifier '%s' is not allowed here." % modifier)

    def declare_assignment_expression_target(self, name, type, pos):
        # In most cases declares the variable as normal.
        # For generator expressions and comprehensions the variable is declared in their parent
        return self.declare_var(name, type, pos)

    def declare_builtin(self, name, pos):
        name = self.mangle_class_private_name(name)
        return self.outer_scope.declare_builtin(name, pos)

    def _declare_pyfunction(self, name, pos, visibility='extern', entry=None):
        if entry and not entry.type.is_cfunction:
            error(pos, "'%s' already declared" % name)
            error(entry.pos, "Previous declaration is here")
        entry = self.declare_var(name, py_object_type, pos, visibility=visibility)
        entry.signature = pyfunction_signature
        self.pyfunc_entries.append(entry)
        return entry

    def declare_pyfunction(self, name, pos, allow_redefine=False, visibility='extern'):
        # Add an entry for a Python function.
        entry = self.lookup_here(name)
        if not allow_redefine:
            return self._declare_pyfunction(name, pos, visibility=visibility, entry=entry)
        if entry:
            if entry.type.is_unspecified:
                entry.type = py_object_type
            elif entry.type is not py_object_type:
                return self._declare_pyfunction(name, pos, visibility=visibility, entry=entry)
        else:  # declare entry stub
            self.declare_var(name, py_object_type, pos, visibility=visibility)
        entry = self.declare_var(None, py_object_type, pos,
                                 cname=name, visibility='private')
        entry.name = EncodedString(name)
        entry.qualified_name = self.qualify_name(name)
        entry.signature = pyfunction_signature
        entry.is_anonymous = True
        return entry

    def declare_lambda_function(self, lambda_name, pos):
        # Add an entry for an anonymous Python function.
        func_cname = self.mangle(Naming.lambda_func_prefix + 'funcdef_', lambda_name)
        pymethdef_cname = self.mangle(Naming.lambda_func_prefix + 'methdef_', lambda_name)
        qualified_name = self.qualify_name(lambda_name)

        entry = self.declare(None, func_cname, py_object_type, pos, 'private')
        entry.name = EncodedString(lambda_name)
        entry.qualified_name = qualified_name
        entry.pymethdef_cname = pymethdef_cname
        entry.func_cname = func_cname
        entry.signature = pyfunction_signature
        entry.is_anonymous = True
        return entry

    def add_lambda_def(self, def_node):
        self.lambda_defs.append(def_node)

    def register_pyfunction(self, entry):
        self.pyfunc_entries.append(entry)

    def declare_cfunction(self, name, type, pos,
                          cname=None, visibility='private', api=0, in_pxd=0,
                          defining=0, modifiers=(), utility_code=None, overridable=False):
        # Add an entry for a C function.
        if not cname:
            if visibility != 'private' or api:
                cname = name
            else:
                cname = self.mangle(Naming.func_prefix, name)
        inline_in_pxd = 'inline' in modifiers and in_pxd and defining
        if inline_in_pxd:
            # in_pxd does special things that we don't want to apply to inline functions
            in_pxd = False
        entry = self.lookup_here(name)
        if entry:
            if not in_pxd and visibility != entry.visibility and visibility == 'extern':
                # Previously declared, but now extern => treat this
                # as implementing the function, using the new cname
                defining = True
                visibility = entry.visibility
                entry.cname = cname
                entry.func_cname = cname
            if visibility != 'private' and visibility != entry.visibility:
                warning(pos, "Function '%s' previously declared as '%s', now as '%s'" % (
                    name, entry.visibility, visibility), 1)
            if overridable != entry.is_overridable:
                warning(pos, "Function '%s' previously declared as '%s'" % (
                    name, 'cpdef' if overridable else 'cdef'), 1)
            if entry.type.same_as(type):
                # Fix with_gil vs nogil.
                entry.type = entry.type.with_with_gil(type.with_gil)
            else:
                if visibility == 'extern' and entry.visibility == 'extern':
                    can_override = self.is_builtin_scope
                    if self.is_cpp():
                        can_override = True
                    elif cname and not can_override:
                        # if all alternatives have different cnames,
                        # it's safe to allow signature overrides
                        for alt_entry in entry.all_alternatives():
                            if not alt_entry.cname or cname == alt_entry.cname:
                                break  # cname not unique!
                        else:
                            can_override = True
                    if can_override:
                        temp = self.add_cfunction(name, type, pos, cname, visibility, modifiers)
                        temp.overloaded_alternatives = entry.all_alternatives()
                        if entry.specialiser is not None:
                            temp.specialiser = entry.specialiser
                        entry = temp
                    else:
                        warning(pos, "Function signature does not match previous declaration", 1)
                        entry.type = type
                elif not in_pxd and entry.defined_in_pxd and type.compatible_signature_with(entry.type):
                    # TODO: check that this was done by a signature optimisation and not a user error.
                    #warning(pos, "Function signature does not match previous declaration", 1)

                    # Cython can't assume anything about cimported functions declared without
                    # an exception value. This is a performance problem mainly for nogil functions.
                    if entry.type.nogil and entry.type.exception_value is None and type.exception_value:
                        performance_hint(
                            entry.pos,
                            f"No exception value declared for '{entry.name}' in pxd file.\n"
                            "Users cimporting this function and calling it without the gil "
                            "will always require an exception check.\n"
                            "Suggest adding an explicit exception value.",
                            self)
                    entry.type = type
                else:
                    error(pos, "Function signature does not match previous declaration")
        else:
            entry = self.add_cfunction(name, type, pos, cname, visibility, modifiers)
            entry.func_cname = cname
            entry.is_overridable = overridable
        if inline_in_pxd:
            entry.inline_func_in_pxd = True
        if in_pxd and visibility != 'extern':
            entry.defined_in_pxd = 1
        if api:
            entry.api = 1
        if not defining and not in_pxd and visibility != 'extern':
            error(pos, "Non-extern C function '%s' declared but not defined" % name)
        if defining:
            entry.is_implemented = True
        if modifiers:
            entry.func_modifiers = modifiers
        if utility_code:
            assert not entry.utility_code, "duplicate utility code definition in entry %s (%s)" % (name, cname)
            entry.utility_code = utility_code
        if overridable:
            # names of cpdef functions can be used as variables and can be assigned to
            var_entry = Entry(name, cname, py_object_type)   # FIXME: cname?
            var_entry.qualified_name = self.qualify_name(name)
            var_entry.is_variable = 1
            var_entry.is_pyglobal = 1
            var_entry.scope = entry.scope
            entry.as_variable = var_entry
        type.entry = entry
        if (type.exception_check and type.exception_value is None and type.nogil and
                not pos[0].in_utility_code and
                # don't warn about external functions here - the user likely can't do anything
                defining and not in_pxd and not inline_in_pxd):
            PyrexTypes.write_noexcept_performance_hint(
                pos, self, function_name=name, void_return=type.return_type.is_void)
        return entry

    def declare_cgetter(self, name, return_type, pos=None, cname=None,
                        visibility="private", modifiers=(), defining=False, **cfunc_type_config):
        assert all(
            k in ('exception_value', 'exception_check', 'nogil', 'with_gil', 'is_const_method', 'is_static_method')
            for k in cfunc_type_config
        )
        cfunc_type = PyrexTypes.CFuncType(
            return_type,
            [PyrexTypes.CFuncTypeArg("self", self.parent_type, None)],
            **cfunc_type_config)
        entry = self.declare_cfunction(
            name, cfunc_type, pos, cname=None, visibility=visibility, modifiers=modifiers, defining=defining)
        entry.is_cgetter = True
        if cname is not None:
            entry.func_cname = cname
        return entry

    def add_cfunction(self, name, type, pos, cname, visibility, modifiers, inherited=False):
        # Add a C function entry without giving it a func_cname.
        entry = self.declare(name, cname, type, pos, visibility)
        entry.is_cfunction = 1
        if modifiers:
            entry.func_modifiers = modifiers
        if inherited or type.is_fused:
            self.cfunc_entries.append(entry)
        else:
            # For backwards compatibility reasons, we must keep all non-fused methods
            # before all fused methods, but separately for each type.
            i = len(self.cfunc_entries)
            for cfunc_entry in reversed(self.cfunc_entries):
                if cfunc_entry.is_inherited or not cfunc_entry.type.is_fused:
                    break
                i -= 1
            self.cfunc_entries.insert(i, entry)
        return entry

    def find(self, name, pos):
        # Look up name, report error if not found.
        entry = self.lookup(name)
        if entry:
            return entry
        else:
            error(pos, "'%s' is not declared" % name)

    def find_imported_module(self, path, pos):
        # Look up qualified name, must be a module, report error if not found.
        # Path is a list of names.
        scope = self
        for name in path:
            entry = scope.find(name, pos)
            if not entry:
                return None
            if entry.as_module:
                scope = entry.as_module
            else:
                error(pos, "'%s' is not a cimported module" % '.'.join(path))
                return None
        return scope

    def lookup(self, name):
        # Look up name in this scope or an enclosing one.
        # Return None if not found.

        mangled_name = self.mangle_class_private_name(name)
        entry = (self.lookup_here(name)  # lookup here also does mangling
                or (self.outer_scope and self.outer_scope.lookup(mangled_name))
                or None)
        if entry:
            return entry

        # look up the original name in the outer scope
        # Not strictly Python behaviour but see https://github.com/cython/cython/issues/3544
        entry = (self.outer_scope and self.outer_scope.lookup(name)) or None
        if entry and entry.is_pyglobal:
            self._emit_class_private_warning(entry.pos, name)
        return entry

    def lookup_here(self, name):
        # Look up in this scope only, return None if not found.

        entry = self.entries.get(self.mangle_class_private_name(name), None)
        if entry:
            return entry
        # Also check the unmangled name in the current scope
        # (even if mangling should give us something else).
        # This is to support things like global __foo which makes a declaration for __foo
        return self.entries.get(name, None)

    def lookup_here_unmangled(self, name):
        return self.entries.get(name, None)

    def lookup_assignment_expression_target(self, name):
        # For most cases behaves like "lookup_here".
        # However, it does look outwards for comprehension and generator expression scopes
        return self.lookup_here(name)

    def lookup_target(self, name):
        # Look up name in this scope only. Declare as Python
        # variable if not found.
        entry = self.lookup_here(name)
        if not entry:
            entry = self.lookup_here_unmangled(name)
            if entry and entry.is_pyglobal:
                self._emit_class_private_warning(entry.pos, name)
        if not entry:
            entry = self.declare_var(name, py_object_type, None)
        return entry

    def _type_or_specialized_type_from_entry(self, entry):
        if entry and entry.is_type:
            if entry.type.is_fused and self.fused_to_specific:
                return entry.type.specialize(self.fused_to_specific)
            return entry.type

    def lookup_type(self, name):
        entry = self.lookup(name)
        # The logic here is:
        #  1. if entry is a type then return it (and maybe specialize it)
        #  2. if the entry comes from a known standard library import then follow that
        #  3. repeat step 1 with the (possibly) updated entry

        tp = self._type_or_specialized_type_from_entry(entry)
        if tp:
            return tp
        # allow us to find types from the "typing" module and similar
        if entry and entry.known_standard_library_import:
            from .Builtin import get_known_standard_library_entry
            entry = get_known_standard_library_entry(entry.known_standard_library_import)
        return self._type_or_specialized_type_from_entry(entry)

    def lookup_operator(self, operator, operands):
        if operands[0].type.is_cpp_class:
            obj_type = operands[0].type
            method = obj_type.scope.lookup("operator%s" % operator)
            if method is not None:
                arg_types = [arg.type for arg in operands[1:]]
                res = PyrexTypes.best_match(arg_types, method.all_alternatives())
                if res is not None:
                    return res
        function = self.lookup("operator%s" % operator)
        function_alternatives = []
        if function is not None:
            function_alternatives = function.all_alternatives()

        # look-up nonmember methods listed within a class
        method_alternatives = []
        if len(operands) == 2:  # binary operators only
            for n in range(2):
                if operands[n].type.is_cpp_class:
                    obj_type = operands[n].type
                    method = obj_type.scope.lookup("operator%s" % operator)
                    if method is not None:
                        method_alternatives += method.all_alternatives()

        if (not method_alternatives) and (not function_alternatives):
            return None

        # select the unique alternatives
        all_alternatives = list(set(method_alternatives + function_alternatives))

        return PyrexTypes.best_match([arg.type for arg in operands],
                                     all_alternatives)

    def lookup_operator_for_types(self, pos, operator, types):
        from .Nodes import Node
        class FakeOperand(Node):
            pass
        operands = [FakeOperand(pos, type=type) for type in types]
        return self.lookup_operator(operator, operands)

    def _emit_class_private_warning(self, pos, name):
        warning(pos, "Global name %s matched from within class scope "
                            "in contradiction to Python 'class private name' rules. "
                            "This may change in a future release." % name, 1)

    def use_utility_code(self, new_code):
        self.global_scope().use_utility_code(new_code)

    def use_entry_utility_code(self, entry):
        self.global_scope().use_entry_utility_code(entry)

    def defines_any(self, names):
        # Test whether any of the given names are defined in this scope.
        for name in names:
            if name in self.entries:
                return 1
        return 0

    def defines_any_special(self, names):
        # Test whether any of the given names are defined as special methods in this scope.
        for name in names:
            if name in self.entries and self.entries[name].is_special:
                return 1
        return 0

    def infer_types(self):
        from .TypeInference import get_type_inferer
        get_type_inferer().infer_types(self)

    def is_cpp(self):
        outer = self.outer_scope
        if outer is None:
            return False
        else:
            return outer.is_cpp()

    def add_include_file(self, filename, verbatim_include=None, late=False):
        self.outer_scope.add_include_file(filename, verbatim_include, late)

    def name_in_module_state(self, cname):
        # TODO - override to give more choices depending on the type of scope
        # e.g. slot, function, method
        return f"{Naming.modulestateglobal_cname}->{cname}"

    def find_shared_usages_of_type(self, type_to_find, _seen_scopes=None):
        if _seen_scopes is None:
            _seen_scopes = set()
        include_all_entries = not self.is_module_scope
        for entry in self.entries.values():
            if not (include_all_entries or entry.defined_in_pxd or entry.visibility == "public" or entry.api):
                continue
            entry_subtypes = PyrexTypes.get_all_subtypes(entry.type)
            if any(type_to_find == sub_tp for sub_tp in entry_subtypes):
                return True
            type_scope = getattr(entry.type, "scope", None)
            if type_scope is None or type_scope in _seen_scopes:
                continue
            _seen_scopes.add(type_scope)
            if type_scope.find_shared_usages_of_type(type_to_find, _seen_scopes):
                return True
        return False


class PreImportScope(Scope):

    namespace_cname = Naming.preimport_cname

    def __init__(self):
        Scope.__init__(self, Options.pre_import, None, None)

    def declare_builtin(self, name, pos):
        entry = self.declare(name, name, py_object_type, pos, 'private')
        entry.is_variable = True
        entry.is_pyglobal = True
        return entry


class BuiltinScope(Scope):
    #  The builtin namespace.

    is_builtin_scope = True

    def __init__(self):
        if Options.pre_import is None:
            Scope.__init__(self, "__builtin__", None, None)
        else:
            Scope.__init__(self, "__builtin__", PreImportScope(), None)
        self.type_names = {}

    def lookup(self, name, language_level=None):
        # 'language_level' is passed by ModuleScope
        if name == 'unicode' or name == 'basestring':
            # Keep recognising 'unicode' and 'basestring' in legacy code but map them to 'str'.
            name = 'str'
        elif name == 'long' and language_level == 2:
            # Keep recognising 'long' in legacy Py2 code but map it to 'int'.
            name = 'int'
        return Scope.lookup(self, name)

    def declare_builtin(self, name, pos):
        if name not in Code.KNOWN_PYTHON_BUILTINS:
            if self.outer_scope is not None:
                return self.outer_scope.declare_builtin(name, pos)
            else:
                if Options.error_on_unknown_names:
                    error(pos, "undeclared name not builtin: %s" % name)
                else:
                    warning(pos, "undeclared name not builtin: %s" % name, 2)

    def declare_builtin_cfunction(self, name, type, cname, python_equiv=None, utility_code=None, specialiser=None):
        # If python_equiv == "*", the Python equivalent has the same name
        # as the entry, otherwise it has the name specified by python_equiv.
        name = EncodedString(name)
        entry = self.declare_cfunction(name, type, None, cname, visibility='extern', utility_code=utility_code)
        if specialiser is not None:
            entry.specialiser = specialiser
        if python_equiv:
            if python_equiv == "*":
                python_equiv = name
            else:
                python_equiv = EncodedString(python_equiv)
            var_entry = Entry(python_equiv, python_equiv, py_object_type)
            var_entry.qualified_name = self.qualify_name(name)
            var_entry.is_variable = 1
            var_entry.is_builtin = 1
            var_entry.utility_code = utility_code
            var_entry.scope = entry.scope
            entry.as_variable = var_entry
        return entry

    def declare_builtin_type(self, name, cname,
                             objstruct_cname=None, type_class=PyrexTypes.BuiltinObjectType,
                             utility_code=None):
        name = EncodedString(name)
        type = type_class(name, cname, objstruct_cname)
        scope = CClassScope(name, outer_scope=None, visibility='extern', parent_type=type)
        scope.directives = {}
        type.set_scope(scope)
        self.type_names[name] = 1

        entry = self.declare_type(name, type, None, visibility='extern')
        if utility_code:
            entry.utility_code = utility_code
        if name == 'range' and 'xrange' not in self.entries:
            # Keep supporting legacy Py2 'xrange' because it's still in use.
            self.entries['xrange'] = entry

        var_entry = Entry(
            name=entry.name,
            type=self.lookup('type').type,  # make sure "type" is the first type declared...
            pos=entry.pos,
            cname=entry.type.typeptr_cname,
        )
        var_entry.qualified_name = self.qualify_name(name)
        var_entry.is_variable = 1
        var_entry.is_cglobal = 1
        var_entry.is_readonly = 1
        var_entry.is_builtin = 1
        var_entry.scope = self
        if Options.cache_builtins:
            var_entry.is_const = True
        if utility_code:
            var_entry.utility_code = utility_code
        entry.as_variable = var_entry

        return type

    def builtin_scope(self):
        return self

    def handle_already_declared_name(self, name, cname, type, pos, visibility, copy_entry=False):
        # Overriding is OK in the builtin scope
        return None


const_counter = 1  # As a temporary solution for compiling code in pxds

class ModuleScope(Scope):
    # module_name          string             Python name of the module
    # module_cname         string             C name of Python module object
    # #module_dict_cname   string             C name of module dict object
    # method_table_cname   string             C name of method table
    # doc                  string             Module doc string
    # doc_cname            string             C name of module doc string
    # utility_code_list    [UtilityCode]      Queuing utility codes for forwarding to Code.py
    # c_includes           {key: IncludeCode} C headers or verbatim code to be generated
    #                                         See process_include() for more documentation
    # identifier_to_entry  {string : Entry}   Map identifier string const to entry
    # context              Context
    # parent_module        Scope              Parent in the import namespace
    # module_entries       {string : Entry}   For cimport statements
    # type_names           {string : 1}       Set of type names (used during parsing)
    # included_files       [string]           Cython sources included with 'include'
    # pxd_file_loaded      boolean            Corresponding .pxd file has been processed
    # cimported_modules    [ModuleScope]      Modules imported with cimport
    # types_imported       {PyrexType}        Set of types for which import code generated
    # has_import_star      boolean            Module contains import *
    # cpp                  boolean            Compiling a C++ file
    # is_cython_builtin    boolean            Is this the Cython builtin scope (or a child scope)
    # is_package           boolean            Is this a package module? (__init__)

    is_module_scope = 1
    has_import_star = 0
    is_cython_builtin = 0
    old_style_globals = 0
    namespace_cname_is_type = False
    scope_predefined_names = [
        '__builtins__', '__name__', '__file__', '__doc__', '__path__',
        '__spec__', '__loader__', '__package__', '__cached__',
    ]

    def __init__(self, name, parent_module, context, is_package=False):
        from . import Builtin
        self.parent_module = parent_module
        outer_scope = Builtin.builtin_scope
        Scope.__init__(self, name, outer_scope, parent_module)
        self.is_package = is_package
        self.module_name = name
        self.module_name = EncodedString(self.module_name)
        self._context = context
        self.module_cname = Naming.module_cname
        self.module_dict_cname = Naming.moddict_cname
        self.method_table_cname = Naming.methtable_cname
        self.doc = ""
        self.doc_cname = Naming.moddoc_cname
        self.utility_code_list = []
        self.module_entries = {}
        self.c_includes = {}
        self.type_names = dict(outer_scope.type_names)
        self.pxd_file_loaded = 0
        self.cimported_modules = []
        self.types_imported = set()
        self.included_files = []
        self.has_extern_class = 0
        self.cached_builtins = []
        self.undeclared_cached_builtins = []
        self.namespace_cname = self.module_cname
        self._cached_tuple_types = {}
        self._cached_defaults_c_class_entries = {}
        self.process_include(Code.IncludeCode("Python.h", initial=True))

    def qualifying_scope(self):
        return self.parent_module

    @property
    def context(self):
        return self._context

    def global_scope(self):
        return self

    def lookup(self, name, language_level=None):
        entry = self.lookup_here(name)
        if entry is not None:
            return entry

        if language_level is None:
            language_level = self.context.language_level if self.context is not None else 3
        return self.outer_scope.lookup(name, language_level=language_level)

    def declare_tuple_type(self, pos, components):
        components = tuple(components)
        try:
            ttype = self._cached_tuple_types[components]
        except KeyError:
            ttype = self._cached_tuple_types[components] = PyrexTypes.c_tuple_type(components)
        cname = ttype.cname
        entry = self.lookup_here(cname)
        if not entry:
            scope = StructOrUnionScope(cname)
            for ix, component in enumerate(components):
                scope.declare_var(name="f%s" % ix, type=component, pos=pos)
            struct_entry = self.declare_struct_or_union(
                cname + '_struct', 'struct', scope, typedef_flag=True, pos=pos, cname=cname)
            self.type_entries.remove(struct_entry)
            ttype.struct_entry = struct_entry
            entry = self.declare_type(cname, ttype, pos, cname)
        ttype.entry = entry
        return entry

    def declare_defaults_c_class(self, pos, components):
        # returns an entry (for the c-class)
        components = tuple(components)
        try:
            return self._cached_defaults_c_class_entries[components]
        except KeyError:
            pass

        cname = self.next_id(Naming.defaults_struct_prefix)
        cname = EncodedString(cname)
        entry = self._cached_defaults_c_class_entries[components] = self.declare_c_class(
            cname, pos, defining=True, implementing=True,
            objstruct_cname=cname)
        self.check_c_class(entry)
        entry.type.is_final_type = True
        scope = entry.type.scope
        scope.is_internal = True
        scope.is_defaults_class_scope = True

        # zero pad the argument number so they can be sorted
        num_zeros = len(str(len(components)))
        build_argname = ("arg{:0>%dd}" % num_zeros).format
        for n, type_ in enumerate(components):
            arg_name = EncodedString(build_argname(n))
            scope.declare_var(arg_name, type_, pos=None, is_cdef=True)
        return entry

    def declare_builtin(self, name, pos):
        if name not in Code.KNOWN_PYTHON_BUILTINS \
               and name not in Code.renamed_py2_builtins_map \
               and name not in Code.uncachable_builtins:
            if self.has_import_star:
                entry = self.declare_var(name, py_object_type, pos)
                return entry
            else:
                if Options.error_on_unknown_names:
                    error(pos, "undeclared name not builtin: %s" % name)
                else:
                    warning(pos, "undeclared name not builtin: %s" % name, 2)
                # unknown - assume it's builtin and look it up at runtime
                entry = self.declare(name, None, py_object_type, pos, 'private')
                entry.is_builtin = 1
                return entry
        if Options.cache_builtins:
            for entry in self.cached_builtins:
                if entry.name == name:
                    return entry
        if name == 'globals' and not self.old_style_globals:
            return self.outer_scope.lookup('__Pyx_Globals')
        else:
            entry = self.declare(None, None, py_object_type, pos, 'private')
        if Options.cache_builtins and name not in Code.uncachable_builtins:
            entry.is_builtin = 1
            entry.is_const = 1  # cached
            entry.name = name
            entry.cname = Naming.builtin_prefix + name
            self.cached_builtins.append(entry)
            self.undeclared_cached_builtins.append(entry)
        else:
            entry.is_builtin = 1
            entry.name = name
        entry.qualified_name = self.builtin_scope().qualify_name(name)
        return entry

    def find_module(self, module_name, pos, relative_level=-1):
        # Find a module in the import namespace, interpreting
        # relative imports relative to this module's parent.
        # Finds and parses the module's .pxd file if the module
        # has not been referenced before.
        is_relative_import = relative_level is not None and relative_level > 0
        from_module = None
        absolute_fallback = False
        if relative_level is not None and relative_level > 0:
            # explicit relative cimport
            # error of going beyond top-level is handled in cimport node
            from_module = self

            top_level = 1 if self.is_package else 0
            # * top_level == 1 when file is __init__.pyx, current package (from_module) is the current module
            #   i.e. dot in `from . import ...` points to the current package
            # * top_level == 0 when file is regular module, current package (from_module) is parent module
            #   i.e. dot in `from . import ...` points to the package where module is placed
            while relative_level > top_level and from_module:
                from_module = from_module.parent_module
                relative_level -= 1

        elif relative_level != 0:
            # -1 or None: try relative cimport first, then absolute
            from_module = self.parent_module
            absolute_fallback = True

        module_scope = self.global_scope()
        return module_scope.context.find_module(
            module_name, from_module=from_module, pos=pos, absolute_fallback=absolute_fallback, relative_import=is_relative_import)

    def find_submodule(self, name, as_package=False):
        # Find and return scope for a submodule of this module,
        # creating a new empty one if necessary. Doesn't parse .pxd.
        if '.' in name:
            name, submodule = name.split('.', 1)
        else:
            submodule = None
        scope = self.lookup_submodule(name)
        if not scope:
            scope = ModuleScope(name, parent_module=self, context=self.context, is_package=True if submodule else as_package)
            self.module_entries[name] = scope
        if submodule:
            scope = scope.find_submodule(submodule, as_package=as_package)
        return scope

    def lookup_submodule(self, name):
        # Return scope for submodule of this module, or None.
        if '.' in name:
            name, submodule = name.split('.', 1)
        else:
            submodule = None
        module = self.module_entries.get(name, None)
        if submodule and module is not None:
            module = module.lookup_submodule(submodule)
        return module

    def add_include_file(self, filename, verbatim_include=None, late=False):
        """
        Add `filename` as include file. Add `verbatim_include` as
        verbatim text in the C file.
        Both `filename` and `verbatim_include` can be `None` or empty.
        """
        inc = Code.IncludeCode(filename, verbatim_include, late=late)
        self.process_include(inc)

    def process_include(self, inc):
        """
        Add `inc`, which is an instance of `IncludeCode`, to this
        `ModuleScope`. This either adds a new element to the
        `c_includes` dict or it updates an existing entry.

        In detail: the values of the dict `self.c_includes` are
        instances of `IncludeCode` containing the code to be put in the
        generated C file. The keys of the dict are needed to ensure
        uniqueness in two ways: if an include file is specified in
        multiple "cdef extern" blocks, only one `#include` statement is
        generated. Second, the same include might occur multiple times
        if we find it through multiple "cimport" paths. So we use the
        generated code (of the form `#include "header.h"`) as dict key.

        If verbatim code does not belong to any include file (i.e. it
        was put in a `cdef extern from *` block), then we use a unique
        dict key: namely, the `sortkey()`.

        One `IncludeCode` object can contain multiple pieces of C code:
        one optional "main piece" for the include file and several other
        pieces for the verbatim code. The `IncludeCode.dict_update`
        method merges the pieces of two different `IncludeCode` objects
        if needed.
        """
        key = inc.mainpiece()
        if key is None:
            key = inc.sortkey()
        inc.dict_update(self.c_includes, key)
        inc = self.c_includes[key]

    def add_imported_module(self, scope):
        if scope not in self.cimported_modules:
            for inc in scope.c_includes.values():
                self.process_include(inc)
            self.cimported_modules.append(scope)
            for m in scope.cimported_modules:
                self.add_imported_module(m)

    def add_imported_entry(self, name, entry, pos):
        if entry.is_pyglobal:
            # Allow cimports to follow imports.
            entry.is_variable = True
        if entry not in self.entries:
            self.entries[name] = entry
        else:
            warning(pos, "'%s' redeclared  " % name, 0)

    def declare_module(self, name, scope, pos):
        # Declare a cimported module. This is represented as a
        # Python module-level variable entry with a module
        # scope attached to it. Reports an error and returns
        # None if previously declared as something else.
        entry = self.lookup_here(name)
        if entry:
            if entry.is_pyglobal and entry.as_module is scope:
                return entry  # Already declared as the same module
            if not (entry.is_pyglobal and not entry.as_module):
                # SAGE -- I put this here so Pyrex
                # cimport's work across directories.
                # Currently it tries to multiply define
                # every module appearing in an import list.
                # It shouldn't be an error for a module
                # name to appear again, and indeed the generated
                # code compiles fine.
                return entry
        else:
            entry = self.declare_var(name, py_object_type, pos)
            entry.is_variable = 0
        entry.as_module = scope
        self.add_imported_module(scope)
        return entry

    def declare_var(self, name, type, pos,
                    cname=None, visibility='private',
                    api=False, in_pxd=False, is_cdef=False, pytyping_modifiers=None):
        # Add an entry for a global variable. If it is a Python
        # object type, and not declared with cdef, it will live
        # in the module dictionary, otherwise it will be a C
        # global variable.
        if visibility not in ('private', 'public', 'extern'):
            error(pos, "Module-level variable cannot be declared %s" % visibility)
        self._reject_pytyping_modifiers(pos, pytyping_modifiers, ('typing.Optional',))  # let's allow at least this one
        if not is_cdef:
            if type is unspecified_type:
                type = py_object_type
            if not (type.is_pyobject and not type.is_extension_type):
                raise InternalError(
                    "Non-cdef global variable is not a generic Python object")
        if (is_cdef and visibility != "extern"
                and self.directives['subinterpreters_compatible'] != "no"):
            extra_warning = ""
            pyobject_warning = ""
            if type.is_pyobject:
                extra_warning = "\nPython objects should not be shared between interpreters"
                pyobject_warning = "Python "
            warning(
                pos,
                f"Global cdef {pyobject_warning}variable used with subinterpreter support enabled.\n"
                "This variable is not currently in the per-interpreter module state "
                "but this will likely change in future releases." +
                extra_warning,
                2+(1 if extra_warning else 0))

        if not cname:
            defining = not in_pxd
            if visibility == 'extern' or (visibility == 'public' and defining):
                cname = name
            else:
                cname = self.mangle(Naming.var_prefix, name)

        entry = self.lookup_here(name)
        if entry and entry.defined_in_pxd:
            #if visibility != 'private' and visibility != entry.visibility:
            #    warning(pos, "Variable '%s' previously declared as '%s'" % (name, entry.visibility), 1)
            if not entry.type.same_as(type):
                if visibility == 'extern' and entry.visibility == 'extern':
                    warning(pos, "Variable '%s' type does not match previous declaration" % name, 1)
                    entry.type = type
                #else:
                #    error(pos, "Variable '%s' type does not match previous declaration" % name)
            if entry.visibility != "private":
                mangled_cname = self.mangle(Naming.var_prefix, name)
                if entry.cname == mangled_cname:
                    cname = name
                    entry.cname = name
            if not entry.is_implemented:
                entry.is_implemented = True
                return entry

        entry = Scope.declare_var(self, name, type, pos,
                                  cname=cname, visibility=visibility,
                                  api=api, in_pxd=in_pxd, is_cdef=is_cdef, pytyping_modifiers=pytyping_modifiers)
        if is_cdef:
            entry.is_cglobal = 1
            if entry.type.declaration_value:
                entry.init = entry.type.declaration_value
            self.var_entries.append(entry)
        else:
            entry.is_pyglobal = 1
        if Options.cimport_from_pyx:
            entry.used = 1
        return entry

    def declare_cfunction(self, name, type, pos,
                          cname=None, visibility='private', api=0, in_pxd=0,
                          defining=0, modifiers=(), utility_code=None, overridable=False):
        if not defining and 'inline' in modifiers:
            # TODO(github/1736): Make this an error.
            warning(pos, "Declarations should not be declared inline.", 1)
        # Add an entry for a C function.
        if not cname:
            if visibility == 'extern' or (visibility == 'public' and defining):
                cname = name
            else:
                cname = self.mangle(Naming.func_prefix, name)
        if visibility == 'extern' and type.optional_arg_count:
            error(pos, "Extern functions cannot have default arguments values.")
        entry = self.lookup_here(name)
        if entry and entry.defined_in_pxd:
            if entry.visibility != "private":
                mangled_cname = self.mangle(Naming.func_prefix, name)
                if entry.cname == mangled_cname:
                    cname = name
                    entry.cname = cname
                    entry.func_cname = cname
        entry = Scope.declare_cfunction(
            self, name, type, pos,
            cname=cname, visibility=visibility, api=api, in_pxd=in_pxd,
            defining=defining, modifiers=modifiers, utility_code=utility_code,
            overridable=overridable)
        return entry

    def declare_global(self, name, pos):
        entry = self.lookup_here(name)
        if not entry:
            self.declare_var(name, py_object_type, pos)

    def use_utility_code(self, new_code):
        if new_code is not None:
            self.utility_code_list.append(new_code)

    def use_entry_utility_code(self, entry):
        if entry is None:
            return
        if entry.utility_code:
            self.utility_code_list.append(entry.utility_code)
        if entry.utility_code_definition:
            self.utility_code_list.append(entry.utility_code_definition)
        for tp in PyrexTypes.get_all_subtypes(entry.type):
            if hasattr(tp, "entry") and tp.entry is not entry:
                self.use_entry_utility_code(tp.entry)

    def declare_c_class(self, name, pos, defining=0, implementing=0,
            module_name=None, base_type=None, objstruct_cname=None,
            typeobj_cname=None, typeptr_cname=None, visibility='private',
            typedef_flag=0, api=0, check_size=None,
            buffer_defaults=None, shadow=0):
        # If this is a non-extern typedef class, expose the typedef, but use
        # the non-typedef struct internally to avoid needing forward
        # declarations for anonymous structs.
        if typedef_flag and visibility != 'extern':
            if not (visibility == 'public' or api):
                warning(pos, "ctypedef only valid for 'extern' , 'public', and 'api'", 2)
            objtypedef_cname = objstruct_cname
            typedef_flag = 0
        else:
            objtypedef_cname = None
        #
        #  Look for previous declaration as a type
        #
        entry = self.lookup_here(name)
        if entry and not shadow:
            type = entry.type
            if not (entry.is_type and type.is_extension_type):
                entry = None  # Will cause redeclaration and produce an error
            else:
                scope = type.scope
                if typedef_flag and (not scope or scope.defined):
                    self.check_previous_typedef_flag(entry, typedef_flag, pos)
                if (scope and scope.defined) or (base_type and type.base_type):
                    if base_type and base_type is not type.base_type:
                        error(pos, "Base type does not match previous declaration")
                if base_type and not type.base_type:
                    type.base_type = base_type
        #
        #  Make a new entry if needed
        #
        if not entry or shadow:
            type = PyrexTypes.PyExtensionType(
                name, typedef_flag, base_type, visibility == 'extern', check_size=check_size)
            type.pos = pos
            type.buffer_defaults = buffer_defaults
            if objtypedef_cname is not None:
                type.objtypedef_cname = objtypedef_cname
            if visibility == 'extern':
                type.module_name = module_name
            else:
                type.module_name = self.qualified_name
            if typeptr_cname:
                type.typeptr_cname = typeptr_cname
            else:
                type.typeptr_cname = self.mangle(Naming.typeptr_prefix, name)
            entry = self.declare_type(name, type, pos, visibility = visibility,
                defining = 0, shadow = shadow)
            entry.is_cclass = True
            if objstruct_cname:
                type.objstruct_cname = objstruct_cname
            elif not entry.in_cinclude:
                type.objstruct_cname = self.mangle(Naming.objstruct_prefix, name)
            else:
                error(entry.pos,
                    "Object name required for 'public' or 'extern' C class")
            self.attach_var_entry_to_c_class(entry)
            self.c_class_entries.append(entry)
        #
        #  Check for re-definition and create scope if needed
        #
        if not type.scope:
            if defining or implementing:
                scope = CClassScope(name = name, outer_scope = self,
                    visibility=visibility,
                    parent_type=type)
                scope.directives = self.directives.copy()
                if base_type and base_type.scope:
                    scope.declare_inherited_c_attributes(base_type.scope)
                type.set_scope(scope)
                self.type_entries.append(entry)
        else:
            if defining and type.scope.defined:
                error(pos, "C class '%s' already defined" % name)
            elif implementing and type.scope.implemented:
                error(pos, "C class '%s' already implemented" % name)
        #
        #  Fill in options, checking for compatibility with any previous declaration
        #
        if defining:
            entry.defined_in_pxd = 1
        if implementing:   # So that filenames in runtime exceptions refer to
            entry.pos = pos  # the .pyx file and not the .pxd file
        if visibility != 'private' and entry.visibility != visibility:
            error(pos, "Class '%s' previously declared as '%s'"
                % (name, entry.visibility))
        if api:
            entry.api = 1
        if objstruct_cname:
            if type.objstruct_cname and type.objstruct_cname != objstruct_cname:
                error(pos, "Object struct name differs from previous declaration")
            type.objstruct_cname = objstruct_cname
        if typeobj_cname:
            if type.typeobj_cname and type.typeobj_cname != typeobj_cname:
                error(pos, "Type object name differs from previous declaration")
            type.typeobj_cname = typeobj_cname

        if self.directives.get('final'):
            entry.type.is_final_type = True
        collection_type = self.directives.get('collection_type')
        if collection_type:
            from .UtilityCode import NonManglingModuleScope
            if not isinstance(self, NonManglingModuleScope):
                # TODO - DW would like to make it public, but I'm making it internal-only
                # for now to avoid adding new features without consensus
                error(pos, "'collection_type' is not a public cython directive")
        if collection_type == 'sequence':
            entry.type.has_sequence_flag = True

        # cdef classes are always exported, but we need to set it to
        # distinguish between unused Cython utility code extension classes
        entry.used = True

        #
        # Return new or existing entry
        #
        return entry

    def allocate_vtable_names(self, entry):
        #  If extension type has a vtable, allocate vtable struct and
        #  slot names for it.
        type = entry.type
        if type.base_type and type.base_type.vtabslot_cname:
            #print "...allocating vtabslot_cname because base type has one" ###
            type.vtabslot_cname = "%s.%s" % (
                Naming.obj_base_cname, type.base_type.vtabslot_cname)
        elif type.scope and type.scope.cfunc_entries:
            # one special case here: when inheriting from builtin
            # types, the methods may also be built-in, in which
            # case they won't need a vtable
            entry_count = len(type.scope.cfunc_entries)
            base_type = type.base_type
            while base_type:
                # FIXME: this will break if we ever get non-inherited C methods
                if not base_type.scope or entry_count > len(base_type.scope.cfunc_entries):
                    break
                if base_type.is_builtin_type:
                    # builtin base type defines all methods => no vtable needed
                    return
                base_type = base_type.base_type
            #print "...allocating vtabslot_cname because there are C methods" ###
            type.vtabslot_cname = Naming.vtabslot_cname
        if type.vtabslot_cname:
            #print "...allocating other vtable related cnames" ###
            type.vtabstruct_cname = self.mangle(Naming.vtabstruct_prefix, entry.name)
            type.vtabptr_cname = self.mangle(Naming.vtabptr_prefix, entry.name)

    def check_c_classes_pxd(self):
        # Performs post-analysis checking and finishing up of extension types
        # being implemented in this module. This is called only for the .pxd.
        #
        # Checks all extension types declared in this scope to
        # make sure that:
        #
        #    * The extension type is fully declared
        #
        # Also allocates a name for the vtable if needed.
        #
        for entry in self.c_class_entries:
            # Check defined
            if not entry.type.scope:
                error(entry.pos, "C class '%s' is declared but not defined" % entry.name)

    def check_c_class(self, entry):
        type = entry.type
        name = entry.name
        visibility = entry.visibility
        # Check defined
        if not type.scope:
            error(entry.pos, "C class '%s' is declared but not defined" % name)
        # Generate typeobj_cname
        if visibility != 'extern' and not type.typeobj_cname:
            type.typeobj_cname = self.mangle(Naming.typeobj_prefix, name)
        ## Generate typeptr_cname
        #type.typeptr_cname = self.mangle(Naming.typeptr_prefix, name)
        # Check C methods defined
        if type.scope:
            for method_entry in type.scope.cfunc_entries:
                if not method_entry.is_inherited and not method_entry.func_cname:
                    error(method_entry.pos, "C method '%s' is declared but not defined" %
                        method_entry.name)
        # Allocate vtable name if necessary
        if type.vtabslot_cname:
            #print "ModuleScope.check_c_classes: allocating vtable cname for", self ###
            type.vtable_cname = self.mangle(Naming.vtable_prefix, entry.name)

    def check_c_classes(self):
        # Performs post-analysis checking and finishing up of extension types
        # being implemented in this module. This is called only for the main
        # .pyx file scope, not for cimported .pxd scopes.
        #
        # Checks all extension types declared in this scope to
        # make sure that:
        #
        #    * The extension type is implemented
        #    * All required object and type names have been specified or generated
        #    * All non-inherited C methods are implemented
        #
        # Also allocates a name for the vtable if needed.
        #
        debug_check_c_classes = 0
        if debug_check_c_classes:
            print("Scope.check_c_classes: checking scope " + self.qualified_name)
        for entry in self.c_class_entries:
            if debug_check_c_classes:
                print("...entry %s %s" % (entry.name, entry))
                print("......type = ",  entry.type)
                print("......visibility = ", entry.visibility)
            self.check_c_class(entry)

    def check_c_functions(self):
        # Performs post-analysis checking making sure all
        # defined c functions are actually implemented.
        for name, entry in self.entries.items():
            if entry.is_cfunction:
                if (entry.defined_in_pxd
                        and entry.scope is self
                        and entry.visibility != 'extern'
                        and not entry.in_cinclude
                        and not entry.is_implemented):
                    error(entry.pos, "Non-extern C function '%s' declared but not defined" % name)

    def attach_var_entry_to_c_class(self, entry):
        # The name of an extension class has to serve as both a type
        # name and a variable name holding the type object. It is
        # represented in the symbol table by a type entry with a
        # variable entry attached to it. For the variable entry,
        # we use a read-only C global variable whose name is an
        # expression that refers to the type object.
        from . import Builtin
        var_entry = Entry(name = entry.name,
            type = Builtin.type_type,
            pos = entry.pos,
            cname = entry.type.typeptr_cname)
        var_entry.qualified_name = entry.qualified_name
        var_entry.is_variable = 1
        var_entry.is_cglobal = 1
        var_entry.is_readonly = 1
        var_entry.is_cclass_var_entry = True
        var_entry.scope = entry.scope
        entry.as_variable = var_entry

    def is_cpp(self):
        return self.cpp

    def infer_types(self):
        from .TypeInference import PyObjectTypeInferer
        PyObjectTypeInferer().infer_types(self)


class LocalScope(Scope):
    is_local_scope = True

    # Does the function have a 'with gil:' block?
    has_with_gil_block = False

    # Transient attribute, used for symbol table variable declarations
    _in_with_gil_block = False

    def __init__(self, name, outer_scope, parent_scope = None):
        if parent_scope is None:
            parent_scope = outer_scope
        Scope.__init__(self, name, outer_scope, parent_scope)

    def mangle(self, prefix, name):
        return punycodify_name(prefix + name)

    def declare_arg(self, name, type, pos):
        # Add an entry for an argument of a function.
        name = self.mangle_class_private_name(name)
        cname = self.mangle(Naming.var_prefix, name)
        entry = self.declare(name, cname, type, pos, 'private')
        entry.is_variable = 1
        if type.is_pyobject:
            entry.init = "0"
        entry.is_arg = 1
        #entry.borrowed = 1 # Not using borrowed arg refs for now
        self.arg_entries.append(entry)
        return entry

    def declare_var(self, name, type, pos,
                    cname=None, visibility='private',
                    api=False, in_pxd=False, is_cdef=False, pytyping_modifiers=None):
        name = self.mangle_class_private_name(name)
        # Add an entry for a local variable.
        if visibility in ('public', 'readonly'):
            error(pos, "Local variable cannot be declared %s" % visibility)
        entry = Scope.declare_var(self, name, type, pos,
                                  cname=cname, visibility=visibility,
                                  api=api, in_pxd=in_pxd, is_cdef=is_cdef, pytyping_modifiers=pytyping_modifiers)
        if entry.type.declaration_value:
            entry.init = entry.type.declaration_value
        entry.is_local = 1

        entry.in_with_gil_block = self._in_with_gil_block
        self.var_entries.append(entry)
        return entry

    def declare_global(self, name, pos):
        # Pull entry from global scope into local scope.
        if self.lookup_here(name):
            warning(pos, "'%s' redeclared  ", 0)
        else:
            entry = self.global_scope().lookup_target(name)
            self.entries[name] = entry

    def declare_nonlocal(self, name, pos):
        # Pull entry from outer scope into local scope
        orig_entry = self.lookup_here(name)
        if orig_entry and orig_entry.scope is self and not orig_entry.from_closure:
            error(pos, "'%s' redeclared as nonlocal" % name)
            orig_entry.already_declared_here()
        else:
            entry = self.lookup(name)
            if entry is None or not entry.from_closure:
                error(pos, "no binding for nonlocal '%s' found" % name)

    def _create_inner_entry_for_closure(self, name, entry):
        entry.in_closure = True
        inner_entry = InnerEntry(entry, self)
        inner_entry.is_variable = True
        self.entries[name] = inner_entry
        return inner_entry

    def lookup(self, name):
        # Look up name in this scope or an enclosing one.
        # Return None if not found.

        entry = Scope.lookup(self, name)
        if entry is not None:
            entry_scope = entry.scope
            while entry_scope.is_comprehension_scope:
                entry_scope = entry_scope.outer_scope
            if entry_scope is not self and entry_scope.is_closure_scope:
                if hasattr(entry.scope, "scope_class"):
                    raise InternalError("lookup() after scope class created.")
                # The actual c fragment for the different scopes differs
                # on the outside and inside, so we make a new entry
                return self._create_inner_entry_for_closure(name, entry)
        return entry

    def mangle_closure_cnames(self, outer_scope_cname):
        for scope in self.iter_local_scopes():
            for entry in scope.entries.values():
                if entry.from_closure:
                    cname = entry.outer_entry.cname
                    if self.is_passthrough:
                        entry.cname = cname
                    else:
                        if cname.startswith(Naming.cur_scope_cname):
                            cname = cname[len(Naming.cur_scope_cname)+2:]
                        entry.cname = "%s->%s" % (outer_scope_cname, cname)
                elif entry.in_closure:
                    entry.original_cname = entry.cname
                    entry.cname = "%s->%s" % (Naming.cur_scope_cname, entry.cname)
                    if entry.type.is_cpp_class and entry.scope.directives['cpp_locals']:
                        entry.make_cpp_optional()


class ComprehensionScope(Scope):
    """Scope for comprehensions (but not generator expressions, which use ClosureScope).
    As opposed to generators, these can be easily inlined in some cases, so all
    we really need is a scope that holds the loop variable(s).
    """
    is_comprehension_scope = True

    def __init__(self, outer_scope):
        parent_scope = outer_scope
        # TODO: also ignore class scopes?
        while parent_scope.is_comprehension_scope:
            parent_scope = parent_scope.parent_scope
        name = parent_scope.global_scope().next_id(Naming.genexpr_id_ref)
        Scope.__init__(self, name, outer_scope, parent_scope)
        self.directives = outer_scope.directives
        self.genexp_prefix = "%s%d%s" % (Naming.pyrex_prefix, len(name), name)

        # Class/ExtType scopes are filled at class creation time, i.e. from the
        # module init function or surrounding function.
        while outer_scope.is_comprehension_scope or outer_scope.is_c_class_scope or outer_scope.is_py_class_scope:
            outer_scope = outer_scope.outer_scope
        self.var_entries = outer_scope.var_entries  # keep declarations outside
        outer_scope.subscopes.add(self)

    def mangle(self, prefix, name):
        return '%s%s' % (self.genexp_prefix, self.parent_scope.mangle(prefix, name))

    def declare_var(self, name, type, pos,
                    cname=None, visibility='private',
                    api=False, in_pxd=False, is_cdef=True, pytyping_modifiers=None):
        if type is unspecified_type:
            # if the outer scope defines a type for this variable, inherit it
            outer_entry = self.outer_scope.lookup(name)
            if outer_entry and outer_entry.is_variable:
                type = outer_entry.type  # may still be 'unspecified_type' !
        self._reject_pytyping_modifiers(pos, pytyping_modifiers)
        # the parent scope needs to generate code for the variable, but
        # this scope must hold its name exclusively
        cname = '%s%s' % (self.genexp_prefix, self.parent_scope.mangle(Naming.var_prefix, name or self.next_id()))
        entry = self.declare(name, cname, type, pos, visibility)
        entry.is_variable = True
        if self.parent_scope.is_module_scope:
            entry.is_cglobal = True
        else:
            entry.is_local = True
        entry.in_subscope = True
        self.var_entries.append(entry)
        self.entries[name] = entry
        return entry

    def declare_assignment_expression_target(self, name, type, pos):
        # should be declared in the parent scope instead
        return self.parent_scope.declare_var(name, type, pos)

    def declare_pyfunction(self, name, pos, allow_redefine=False):
        return self.outer_scope.declare_pyfunction(
            name, pos, allow_redefine)

    def declare_lambda_function(self, func_cname, pos):
        return self.outer_scope.declare_lambda_function(func_cname, pos)

    def add_lambda_def(self, def_node):
        return self.outer_scope.add_lambda_def(def_node)

    def lookup_assignment_expression_target(self, name):
        entry = self.lookup_here(name)
        if not entry:
            entry = self.parent_scope.lookup_assignment_expression_target(name)
        return entry


class ClosureScope(LocalScope):

    is_closure_scope = True

    def __init__(self, name, scope_name, outer_scope, parent_scope=None):
        LocalScope.__init__(self, name, outer_scope, parent_scope)
        self.closure_cname = "%s%s" % (Naming.closure_scope_prefix, scope_name)

#    def mangle_closure_cnames(self, scope_var):
#        for entry in self.entries.values() + self.temp_entries:
#            entry.in_closure = 1
#        LocalScope.mangle_closure_cnames(self, scope_var)

#    def mangle(self, prefix, name):
#        return "%s->%s" % (self.cur_scope_cname, name)
#        return "%s->%s" % (self.closure_cname, name)

    def declare_pyfunction(self, name, pos, allow_redefine=False):
        return LocalScope.declare_pyfunction(self, name, pos, allow_redefine, visibility='private')

    def declare_assignment_expression_target(self, name, type, pos):
        return self.declare_var(name, type, pos)


class GeneratorExpressionScope(ClosureScope):
    is_generator_expression_scope = True

    def declare_assignment_expression_target(self, name, type, pos):
        entry = self.parent_scope.declare_var(name, type, pos)
        return self._create_inner_entry_for_closure(name, entry)

    def lookup_assignment_expression_target(self, name):
        entry = self.lookup_here(name)
        if not entry:
            entry = self.parent_scope.lookup_assignment_expression_target(name)
            if entry:
                return self._create_inner_entry_for_closure(name, entry)
        return entry


class StructOrUnionScope(Scope):
    #  Namespace of a C struct or union.

    def __init__(self, name="?"):
        Scope.__init__(self, name, outer_scope=None, parent_scope=None)

    def declare_var(self, name, type, pos,
                    cname=None, visibility='private',
                    api=False, in_pxd=False, is_cdef=False, pytyping_modifiers=None,
                    allow_pyobject=False, allow_memoryview=False, allow_refcounted=False):
        # Add an entry for an attribute.
        if not cname:
            cname = name
            if visibility == 'private':
                cname = c_safe_identifier(cname)
        if type.is_cfunction:
            type = PyrexTypes.CPtrType(type)
        self._reject_pytyping_modifiers(pos, pytyping_modifiers)
        entry = self.declare(name, cname, type, pos, visibility)
        entry.is_variable = 1
        self.var_entries.append(entry)
        if type.is_pyobject:
            if not allow_pyobject:
                error(pos, "C struct/union member cannot be a Python object")
        elif type.is_memoryviewslice:
            if not allow_memoryview:
                # Memory views wrap their buffer owner as a Python object.
                error(pos, "C struct/union member cannot be a memory view")
        elif type.needs_refcounting:
            if not allow_refcounted:
                error(pos, "C struct/union member cannot be reference-counted type '%s'" % type)
        return entry

    def declare_cfunction(self, name, type, pos,
                          cname=None, visibility='private', api=0, in_pxd=0,
                          defining=0, modifiers=(), overridable=False):  # currently no utility code ...
        if overridable:
            error(pos, "C struct/union member cannot be declared 'cpdef'")
        return self.declare_var(name, type, pos,
                                cname=cname, visibility=visibility)


class ClassScope(Scope):
    #  Abstract base class for namespace of
    #  Python class or extension type.
    #
    #  class_name     string   Python name of the class
    #  scope_prefix   string   Additional prefix for names
    #                          declared in the class
    #  doc    string or None   Doc string

    scope_predefined_names = ['__module__', '__qualname__']

    def mangle_class_private_name(self, name):
        # a few utilitycode names need to specifically be ignored
        if name and name.lower().startswith("__pyx_"):
            return name
        if name and name.startswith('__') and not name.endswith('__'):
            name = EncodedString('_%s%s' % (self.class_name.lstrip('_'), name))
        return name

    def __init__(self, name, outer_scope):
        Scope.__init__(self, name, outer_scope, outer_scope)
        self.class_name = name
        self.doc = None

    def lookup(self, name):
        entry = Scope.lookup(self, name)
        if entry:
            return entry
        if name == "classmethod":
            # We don't want to use the builtin classmethod here 'cause it won't do the
            # right thing in this scope (as the class members aren't still functions).
            # Don't want to add a cfunction to this scope 'cause that would mess with
            # the type definition, so we just return the right entry.
            entry = Entry(
                "classmethod",
                "__Pyx_Method_ClassMethod",
                PyrexTypes.CFuncType(
                    py_object_type,
                    [PyrexTypes.CFuncTypeArg("", py_object_type, None)], 0, 0))
            entry.utility_code_definition = Code.UtilityCode.load_cached("ClassMethod", "CythonFunction.c")
            self.use_entry_utility_code(entry)
            entry.is_cfunction = 1
            entry.scope = self.builtin_scope()
        return entry


class PyClassScope(ClassScope):
    #  Namespace of a Python class.
    #
    #  class_obj_cname     string   C variable holding class object

    is_py_class_scope = 1
    namespace_cname_is_type = False

    def declare_var(self, name, type, pos,
                    cname=None, visibility='private',
                    api=False, in_pxd=False, is_cdef=False, pytyping_modifiers=None):
        name = self.mangle_class_private_name(name)
        if type is unspecified_type:
            type = py_object_type
        # Add an entry for a class attribute.
        entry = Scope.declare_var(self, name, type, pos,
                                  cname=cname, visibility=visibility,
                                  api=api, in_pxd=in_pxd, is_cdef=is_cdef, pytyping_modifiers=pytyping_modifiers)
        entry.is_pyglobal = 1
        entry.is_pyclass_attr = 1
        return entry

    def declare_nonlocal(self, name, pos):
        # Pull entry from outer scope into local scope
        orig_entry = self.lookup_here(name)
        if orig_entry and orig_entry.scope is self and not orig_entry.from_closure:
            error(pos, "'%s' redeclared as nonlocal" % name)
            orig_entry.already_declared_here()
        else:
            entry = self.lookup(name)
            if entry is None:
                error(pos, "no binding for nonlocal '%s' found" % name)
            else:
                # FIXME: this works, but it's unclear if it's the
                # right thing to do
                self.entries[name] = entry

    def declare_global(self, name, pos):
        # Pull entry from global scope into local scope.
        if self.lookup_here(name):
            warning(pos, "'%s' redeclared  ", 0)
        else:
            entry = self.global_scope().lookup_target(name)
            self.entries[name] = entry

    def add_default_value(self, type):
        return self.outer_scope.add_default_value(type)


class CClassScope(ClassScope):
    #  Namespace of an extension type.
    #
    #  parent_type           PyExtensionType
    #  #typeobj_cname        string or None
    #  #objstruct_cname      string
    #  method_table_cname    string
    #  getset_table_cname    string
    #  has_pyobject_attrs    boolean  Any PyObject attributes?
    #  has_memoryview_attrs  boolean  Any memory view attributes?
    #  has_explicitly_constructable_class_attrs   boolean  Any attributes that
    #                               need an explicit constructor (e.g. C++ class non-pointers)?
    #  has_cyclic_pyobject_attrs    boolean  Any PyObject attributes that may need GC?
    #  property_entries      [Entry]
    #  defined               boolean  Defined in .pxd file
    #  implemented           boolean  Defined in .pyx file
    #  inherited_var_entries [Entry]  Adapted var entries from base class

    is_c_class_scope = 1
    is_closure_class_scope = False
    is_defaults_class_scope = False

    has_pyobject_attrs = False
    has_memoryview_attrs = False
    has_explicitly_constructable_attrs = False
    has_cyclic_pyobject_attrs = False
    defined = False
    implemented = False

    def __init__(self, name, outer_scope, visibility, parent_type):
        ClassScope.__init__(self, name, outer_scope)
        if visibility != 'extern':
            self.method_table_cname = outer_scope.mangle(Naming.methtab_prefix, name)
            self.getset_table_cname = outer_scope.mangle(Naming.gstab_prefix, name)
        self.property_entries = []
        self.inherited_var_entries = []
        self.parent_type = parent_type
        # Usually parent_type will be an extension type and so the typeptr_cname
        # can be used to calculate the namespace_cname. Occasionally other types
        # are used (e.g. numeric/complex types) and in these cases the typeptr
        # isn't relevant.
        if ((parent_type.is_builtin_type or parent_type.is_extension_type)
                and parent_type.typeptr_cname):
            self.namespace_cname = self.parent_type.typeptr_cname
            self.namespace_cname_is_type = True

    def needs_gc(self):
        # If the type or any of its base types have Python-valued
        # C attributes, then it needs to participate in GC.
        if self.has_cyclic_pyobject_attrs and not self.directives.get('no_gc', False):
            return True
        if self.parent_type.is_external and not self.parent_type.is_builtin_type:
            # It's impossible to really know - external types are often incomplete.
            return True
        base_type = self.parent_type.base_type
        if base_type and base_type.scope is not None:
            return base_type.scope.needs_gc()
        elif self.parent_type.is_builtin_type:
            return not self.parent_type.is_gc_simple
        return False

    def needs_trashcan(self):
        # If the trashcan directive is explicitly set to False,
        # unconditionally disable the trashcan.
        directive = self.directives.get('trashcan')
        if directive is False:
            return False
        # If the directive is set to True and the class has Python-valued
        # C attributes, then it should use the trashcan in tp_dealloc.
        if directive and self.has_cyclic_pyobject_attrs:
            return True
        # Use the trashcan if the base class uses it
        base_type = self.parent_type.base_type
        if base_type and base_type.scope is not None:
            return base_type.scope.needs_trashcan()
        return self.parent_type.builtin_trashcan

    def needs_tp_clear(self):
        """
        Do we need to generate an implementation for the tp_clear slot? Can
        be disabled to keep references for the __dealloc__ cleanup function.
        """
        return self.needs_gc() and not self.directives.get('no_gc_clear', False)

    def may_have_finalize(self):
        """
        This covers cases where we definitely have a __del__ function
        and also cases where one of the base classes could have a __del__
        function but we don't know.
        """
        current_type_scope = self
        while current_type_scope:
            del_entry = current_type_scope.lookup_here("__del__")
            if del_entry and del_entry.is_special:
                return True
            if (current_type_scope.parent_type.is_external or not current_type_scope.implemented or
                    current_type_scope.parent_type.multiple_bases):
                # we don't know if we have __del__, so assume we do and call it
                return True
            current_base_type = current_type_scope.parent_type.base_type
            current_type_scope = current_base_type.scope if current_base_type else None
        return False

    def get_refcounted_entries(self, include_weakref=False,
                               include_gc_simple=True):
        py_attrs = []
        py_buffers = []
        memoryview_slices = []

        for entry in self.var_entries:
            if entry.type.is_pyobject:
                if include_weakref or (self.is_closure_class_scope or entry.name != "__weakref__"):
                    if include_gc_simple or not entry.type.is_gc_simple:
                        py_attrs.append(entry)
            elif entry.type == PyrexTypes.c_py_buffer_type:
                py_buffers.append(entry)
            elif entry.type.is_memoryviewslice:
                memoryview_slices.append(entry)

        have_entries = py_attrs or py_buffers or memoryview_slices
        return have_entries, (py_attrs, py_buffers, memoryview_slices)

    def declare_var(self, name, type, pos,
                    cname=None, visibility='private',
                    api=False, in_pxd=False, is_cdef=False, pytyping_modifiers=None):
        name = self.mangle_class_private_name(name)

        if pytyping_modifiers:
            if "typing.ClassVar" in pytyping_modifiers:
                is_cdef = 0
                if not type.is_pyobject:
                    if not type.equivalent_type:
                        warning(pos, "ClassVar[] requires the type to be a Python object type. Found '%s', using object instead." % type)
                        type = py_object_type
                    else:
                        type = type.equivalent_type
            if  "dataclasses.InitVar" in pytyping_modifiers and not self.is_c_dataclass_scope:
                error(pos, "Use of cython.dataclasses.InitVar does not make sense outside a dataclass")

        if is_cdef:
            # Add an entry for an attribute.
            if self.defined:
                error(pos,
                    "C attributes cannot be added in implementation part of"
                    " extension type defined in a pxd")
            if (not self.is_closure_class_scope and
                    get_slot_table(self.directives).get_special_method_signature(name)):
                error(pos,
                    "The name '%s' is reserved for a special method."
                        % name)
            if not cname:
                cname = name
                if not (self.parent_type.is_external or self.parent_type.entry.api or
                        self.parent_type.entry.visibility == "public"):
                    cname = c_safe_identifier(cname)
                cname = punycodify_name(cname, Naming.unicode_structmember_prefix)
            entry = self.declare(name, cname, type, pos, visibility)
            entry.is_variable = 1
            self.var_entries.append(entry)
            entry.pytyping_modifiers = pytyping_modifiers
            if type.is_cpp_class and visibility != 'extern':
                if self.directives['cpp_locals']:
                    entry.make_cpp_optional()
                else:
                    type.check_nullary_constructor(pos)
            if type.is_memoryviewslice:
                self.has_memoryview_attrs = True
            elif type.needs_explicit_construction(self):
                self.has_explicitly_constructable_attrs = True
            elif type.is_pyobject and (self.is_closure_class_scope or name != '__weakref__'):
                self.has_pyobject_attrs = True
                if (not type.is_builtin_type
                        or not type.scope or type.scope.needs_gc()):
                    self.has_cyclic_pyobject_attrs = True
            if visibility not in ('private', 'public', 'readonly'):
                error(pos,
                    "Attribute of extension type cannot be declared %s" % visibility)
            if visibility in ('public', 'readonly'):
                # If the field is an external typedef, we cannot be sure about the type,
                # so do conversion ourself rather than rely on the CPython mechanism (through
                # a property; made in AnalyseDeclarationsTransform).
                entry.needs_property = True
                if not self.is_closure_class_scope and name == "__weakref__":
                    error(pos, "Special attribute __weakref__ cannot be exposed to Python")
                if not (type.is_pyobject or type.can_coerce_to_pyobject(self)):
                    # we're not testing for coercion *from* Python here - that would fail later
                    error(pos, "C attribute of type '%s' cannot be accessed from Python" % type)
            else:
                entry.needs_property = False
            return entry
        else:
            if type is unspecified_type:
                type = py_object_type
            # Add an entry for a class attribute.
            entry = Scope.declare_var(self, name, type, pos,
                                      cname=cname, visibility=visibility,
                                      api=api, in_pxd=in_pxd, is_cdef=is_cdef, pytyping_modifiers=pytyping_modifiers)
            entry.is_member = 1
            # xxx: is_pyglobal changes behaviour in so many places that I keep it in for now.
            # is_member should be enough later on
            entry.is_pyglobal = 1

            return entry

    def declare_pyfunction(self, name, pos, allow_redefine=False):
        # Add an entry for a method.
        if name in richcmp_special_methods:
            if self.lookup_here('__richcmp__'):
                error(pos, "Cannot define both % and __richcmp__" % name)
        elif name == '__richcmp__':
            for n in richcmp_special_methods:
                if self.lookup_here(n):
                    error(pos, "Cannot define both % and __richcmp__" % n)
        if name == "__new__":
            error(pos, "__new__ method of extension type will change semantics "
                "in a future version of Pyrex and Cython. Use __cinit__ instead.")
        entry = self.declare_var(name, py_object_type, pos,
                                 visibility='extern')
        special_sig = get_slot_table(self.directives).get_special_method_signature(name)
        if special_sig:
            # Special methods get put in the method table with a particular
            # signature declared in advance.
            entry.signature = special_sig
            entry.is_special = 1
        else:
            entry.signature = pymethod_signature
            entry.is_special = 0

        self.pyfunc_entries.append(entry)
        return entry

    def lookup_here(self, name):
        if not self.is_closure_class_scope and name == "__new__":
            name = EncodedString("__cinit__")
        entry = ClassScope.lookup_here(self, name)
        if entry and entry.is_builtin_cmethod:
            if not self.parent_type.is_builtin_type:
                # For subtypes of builtin types, we can only return
                # optimised C methods if the type if final.
                # Otherwise, subtypes may choose to override the
                # method, but the optimisation would prevent the
                # subtype method from being called.
                if not self.parent_type.is_final_type:
                    return None
        return entry

    def declare_cfunction(self, name, type, pos,
                          cname=None, visibility='private', api=0, in_pxd=0,
                          defining=0, modifiers=(), utility_code=None, overridable=False):
        name = self.mangle_class_private_name(name)
        if (get_slot_table(self.directives).get_special_method_signature(name)
                and not self.parent_type.is_builtin_type):
            error(pos, "Special methods must be declared with 'def', not 'cdef'")
        args = type.args
        if not type.is_static_method:
            if not args:
                error(pos, "C method has no self argument")
            elif not self.parent_type.assignable_from(args[0].type):
                error(pos, "Self argument (%s) of C method '%s' does not match parent type (%s)" %
                      (args[0].type, name, self.parent_type))
        entry = self.lookup_here(name)
        if cname is None:
            cname = punycodify_name(c_safe_identifier(name), Naming.unicode_vtabentry_prefix)
        if entry:
            if not entry.is_cfunction:
                error(pos, "'%s' redeclared " % name)
                entry.already_declared_here()
            else:
                if defining and entry.func_cname:
                    error(pos, "'%s' already defined" % name)
                #print "CClassScope.declare_cfunction: checking signature" ###
                if entry.is_final_cmethod and entry.is_inherited:
                    error(pos, "Overriding final methods is not allowed")
                elif type.same_c_signature_as(entry.type, as_cmethod = 1) and type.nogil == entry.type.nogil:
                    # Fix with_gil vs nogil.
                    entry.type = entry.type.with_with_gil(type.with_gil)
                elif type.compatible_signature_with(entry.type, as_cmethod = 1) and type.nogil == entry.type.nogil:
                    if (self.defined and not in_pxd
                            and not type.same_c_signature_as_resolved_type(
                                entry.type, as_cmethod=1, as_pxd_definition=1)):
                        # TODO(robertwb): Make this an error.
                        warning(pos,
                            "Compatible but non-identical C method '%s' not redeclared "
                            "in definition part of extension type '%s'.  "
                            "This may cause incorrect vtables to be generated." % (
                                name, self.class_name), 2)
                        warning(entry.pos, "Previous declaration is here", 2)
                    entry = self.add_cfunction(name, type, pos, cname, visibility='ignore', modifiers=modifiers)
                else:
                    error(pos, "Signature not compatible with previous declaration")
                    error(entry.pos, "Previous declaration is here")
        else:
            if self.defined:
                error(pos,
                    "C method '%s' not previously declared in definition part of"
                    " extension type '%s'" % (name, self.class_name))
            entry = self.add_cfunction(name, type, pos, cname, visibility, modifiers)
        if defining:
            entry.func_cname = self.mangle(Naming.func_prefix, name)
        entry.utility_code = utility_code
        type.entry = entry

        if 'inline' in modifiers:
            entry.is_inline_cmethod = True

        if self.parent_type.is_final_type or entry.is_inline_cmethod or self.directives.get('final'):
            entry.is_final_cmethod = True
            entry.final_func_cname = entry.func_cname
            if not type.is_fused:
                entry.vtable_type = entry.type
                entry.type = type

        return entry

    def add_cfunction(self, name, type, pos, cname, visibility, modifiers, inherited=False):
        # Add a cfunction entry without giving it a func_cname.
        prev_entry = self.lookup_here(name)
        entry = ClassScope.add_cfunction(
            self, name, type, pos, cname, visibility, modifiers, inherited=inherited)
        entry.is_cmethod = 1
        entry.prev_entry = prev_entry
        return entry

    def declare_builtin_cfunction(self, name, type, cname, utility_code = None):
        # overridden methods of builtin types still have their Python
        # equivalent that must be accessible to support bound methods
        name = EncodedString(name)
        entry = self.declare_cfunction(
            name, type, pos=None, cname=cname, visibility='extern', utility_code=utility_code)
        var_entry = Entry(name, name, py_object_type)
        var_entry.qualified_name = name
        var_entry.is_variable = 1
        var_entry.is_builtin = 1
        var_entry.utility_code = utility_code
        var_entry.scope = entry.scope
        entry.as_variable = var_entry
        return entry

    def declare_property(self, name, doc, pos, ctype=None, property_scope=None):
        entry = self.lookup_here(name)
        if entry is None:
            entry = self.declare(name, name, py_object_type if ctype is None else ctype, pos, 'private')
        entry.is_property = True
        if ctype is not None:
            entry.is_cproperty = True
        entry.doc = doc
        if property_scope is None:
            entry.scope = PropertyScope(name, class_scope=self)
        else:
            entry.scope = property_scope
        self.property_entries.append(entry)
        return entry

    def declare_cproperty(self, name, type, cfunc_name, doc=None, pos=None, visibility='extern',
                          nogil=False, with_gil=False, exception_value=None, exception_check=False,
                          utility_code=None):
        """Internal convenience method to declare a C property function in one go.
        """
        property_entry = self.declare_property(name, doc=doc, ctype=type, pos=pos)
        cfunc_entry = property_entry.scope.declare_cfunction(
            name=name,
            type=PyrexTypes.CFuncType(
                type,
                [PyrexTypes.CFuncTypeArg("self", self.parent_type, pos=None)],
                nogil=nogil,
                with_gil=with_gil,
                exception_value=exception_value,
                exception_check=exception_check,
            ),
            cname=cfunc_name,
            utility_code=utility_code,
            visibility=visibility,
            pos=pos,
        )
        return property_entry, cfunc_entry

    def declare_inherited_c_attributes(self, base_scope):
        # Declare entries for all the C attributes of an
        # inherited type, with cnames modified appropriately
        # to work with this type.
        def adapt(cname):
            return "%s.%s" % (Naming.obj_base_cname, base_entry.cname)

        entries = base_scope.inherited_var_entries + base_scope.var_entries
        for base_entry in entries:
            entry = self.declare(
                base_entry.name, adapt(base_entry.cname),
                base_entry.type, None, 'private')
            entry.is_variable = 1
            entry.is_inherited = True
            entry.annotation = base_entry.annotation
            self.inherited_var_entries.append(entry)

        # If the class defined in a pxd, specific entries have not been added.
        # Ensure now that the parent (base) scope has specific entries
        # Iterate over a copy as get_all_specialized_function_types() will mutate
        for base_entry in base_scope.cfunc_entries[:]:
            if base_entry.type.is_fused:
                base_entry.type.get_all_specialized_function_types()

        for base_entry in base_scope.cfunc_entries:
            cname = base_entry.cname
            var_entry = base_entry.as_variable
            is_builtin = var_entry and var_entry.is_builtin
            if not is_builtin:
                cname = adapt(cname)
            entry = self.add_cfunction(
                base_entry.name, base_entry.type, base_entry.pos, cname,
                base_entry.visibility, base_entry.func_modifiers, inherited=True)
            entry.is_inherited = 1
            if base_entry.is_final_cmethod:
                entry.is_final_cmethod = True
                entry.is_inline_cmethod = base_entry.is_inline_cmethod
                if (self.parent_scope == base_scope.parent_scope or
                        entry.is_inline_cmethod):
                    entry.final_func_cname = base_entry.final_func_cname
            if is_builtin:
                entry.is_builtin_cmethod = True
                entry.as_variable = var_entry
            if base_entry.utility_code:
                entry.utility_code = base_entry.utility_code


    def handle_already_declared_name(self, name, cname, type, pos, visibility, copy_entry=True):
        # We want to copy the existing entry instead of modifying it, since this is an override.
        super().handle_already_declared_name(name, cname, type, pos, visibility, copy_entry)

class CppClassScope(Scope):
    #  Namespace of a C++ class.

    is_cpp_class_scope = 1

    default_constructor = None
    type = None

    def __init__(self, name, outer_scope, templates=None):
        Scope.__init__(self, name, outer_scope, None)
        self.directives = outer_scope.directives
        self.inherited_var_entries = []
        if templates is not None:
            for T in templates:
                template_entry = self.declare(
                    T, T, PyrexTypes.TemplatePlaceholderType(T), None, 'extern')
                template_entry.is_type = 1

    def declare_var(self, name, type, pos,
                    cname=None, visibility='extern',
                    api=False, in_pxd=False, is_cdef=False, defining=False, pytyping_modifiers=None):
        # Add an entry for an attribute.
        if not cname:
            cname = name
        self._reject_pytyping_modifiers(pos, pytyping_modifiers)
        entry = self.lookup_here(name)
        if defining and entry is not None:
            if type.is_cfunction:
                entry = self.declare(name, cname, type, pos, visibility)
            elif entry.type.same_as(type):
                # Fix with_gil vs nogil.
                entry.type = entry.type.with_with_gil(type.with_gil)
            else:
                error(pos, "Function signature does not match previous declaration")
        else:
            entry = self.declare(name, cname, type, pos, visibility)
            if type.is_cfunction and not defining:
                entry.is_inherited = 1
        entry.is_variable = 1
        if type.is_cfunction:
            entry.is_cfunction = 1
            if self.type and not self.type.get_fused_types():
                entry.func_cname = "%s::%s" % (self.type.empty_declaration_code(), cname)
        if name != "this" and (defining or name != "<init>"):
            self.var_entries.append(entry)
        return entry

    def declare_cfunction(self, name, type, pos,
                          cname=None, visibility='extern', api=0, in_pxd=0,
                          defining=0, modifiers=(), utility_code=None, overridable=False):
        class_name = self.name.split('::')[-1]
        if name in (class_name, '__init__') and cname is None:
            cname = "%s__init__%s" % (Naming.func_prefix, class_name)
            name = EncodedString('<init>')
            type.return_type = PyrexTypes.CVoidType()
            # This is called by the actual constructor, but need to support
            # arguments that cannot by called by value.
            type.original_args = type.args
            def maybe_ref(arg):
                if arg.type.is_cpp_class and not arg.type.is_reference:
                    return PyrexTypes.CFuncTypeArg(
                        arg.name, PyrexTypes.c_ref_type(arg.type), arg.pos)
                else:
                    return arg
            type.args = [maybe_ref(arg) for arg in type.args]
        elif name == '__dealloc__' and cname is None:
            cname = "%s__dealloc__%s" % (Naming.func_prefix, class_name)
            name = EncodedString('<del>')
            type.return_type = PyrexTypes.CVoidType()
        if name in ('<init>', '<del>') and type.nogil:
            for base in self.type.base_classes:
                base_entry = base.scope.lookup(name)
                if base_entry and not base_entry.type.nogil:
                    error(pos, "Constructor cannot be called without GIL unless all base constructors can also be called without GIL")
                    error(base_entry.pos, "Base constructor defined here.")
        # The previous entries management is now done directly in Scope.declare
        entry = self.declare_var(name, type, pos,
                                 defining=defining,
                                 cname=cname, visibility=visibility)
        entry.utility_code = utility_code
        type.entry = entry
        return entry

    def declare_inherited_cpp_attributes(self, base_class):
        base_scope = base_class.scope
        template_type = base_class
        while getattr(template_type, 'template_type', None):
            template_type = template_type.template_type
        if getattr(template_type, 'templates', None):
            base_templates = [T.name for T in template_type.templates]
        else:
            base_templates = ()
        # Declare entries for all the C++ attributes of an
        # inherited type, with cnames modified appropriately
        # to work with this type.
        for base_entry in base_scope.inherited_var_entries + base_scope.var_entries:
            #constructor/destructor is not inherited
            if base_entry.name in ("<init>", "<del>"):
                continue
            #print base_entry.name, self.entries
            if base_entry.name in self.entries:
                base_entry.name    # FIXME: is there anything to do in this case?
            entry = self.declare(base_entry.name, base_entry.cname,
                base_entry.type, None, 'extern')
            entry.is_variable = 1
            entry.is_inherited = 1
            if base_entry.is_cfunction:
                entry.is_cfunction = 1
                entry.func_cname = base_entry.func_cname
            self.inherited_var_entries.append(entry)
        for base_entry in base_scope.cfunc_entries:
            entry = self.declare_cfunction(base_entry.name, base_entry.type,
                                           base_entry.pos, base_entry.cname,
                                           base_entry.visibility, api=0,
                                           modifiers=base_entry.func_modifiers,
                                           utility_code=base_entry.utility_code)
            entry.is_inherited = 1
        for base_entry in base_scope.type_entries:
            if base_entry.name not in base_templates:
                entry = self.declare_type(base_entry.name, base_entry.type,
                                          base_entry.pos, base_entry.cname,
                                          base_entry.visibility, defining=False)
                entry.is_inherited = 1

    def specialize(self, values, type_entry):
        scope = CppClassScope(self.name, self.outer_scope)
        scope.type = type_entry
        for entry in self.entries.values():
            if entry.is_type:
                scope.declare_type(entry.name,
                                   entry.type.specialize(values),
                                   entry.pos,
                                   entry.cname,
                                   template=1)
            elif entry.type.is_cfunction:
                for e in entry.all_alternatives():
                    scope.declare_cfunction(e.name,
                                            e.type.specialize(values),
                                            e.pos,
                                            e.cname,
                                            utility_code=e.utility_code)
            else:
                scope.declare_var(entry.name,
                                  entry.type.specialize(values),
                                  entry.pos,
                                  entry.cname,
                                  entry.visibility)

        return scope

    def lookup_here(self, name):
        if name == "__init__":
            name = "<init>"
        elif name == "__dealloc__":
            name = "<del>"
        return super(CppClassScope, self).lookup_here(name)

    def is_cpp(self):
        # Whatever the global environment, always treat cppclass with C++ rules.
        # (Cython will emit warnings elsewhere)
        return True


class CppScopedEnumScope(Scope):
    #  Namespace of a ScopedEnum

    def __init__(self, name, outer_scope):
        Scope.__init__(self, name, outer_scope, None)

    def declare_var(self, name, type, pos,
                    cname=None, visibility='extern', pytyping_modifiers=None):
        # Add an entry for an attribute.
        if not cname:
            cname = name
        self._reject_pytyping_modifiers(pos, pytyping_modifiers)
        entry = self.declare(name, cname, type, pos, visibility)
        entry.is_variable = True
        return entry


class PropertyScope(Scope):
    #  Scope holding the __get__, __set__ and __del__ methods for
    #  a property of an extension type.
    #
    #  parent_type   PyExtensionType   The type to which the property belongs

    is_property_scope = 1

    def __init__(self, name, class_scope):
        # outer scope is None for some internal properties
        outer_scope = class_scope.global_scope() if class_scope.outer_scope else None
        Scope.__init__(self, name, outer_scope, parent_scope=class_scope)
        self.parent_type = class_scope.parent_type
        self.directives = class_scope.directives

    def declare_cfunction(self, name, type, pos, *args, **kwargs):
        """Declare a C property function.
        """
        if type.return_type.is_void:
            error(pos, "C property method cannot return 'void'")

        if type.args and type.args[0].type is py_object_type:
            # Set 'self' argument type to extension type.
            type.args[0].type = self.parent_scope.parent_type
        elif len(type.args) != 1:
            error(pos, "C property method must have a single (self) argument")
        elif not (type.args[0].type.is_pyobject or type.args[0].type is self.parent_scope.parent_type):
            error(pos, "C property method must have a single (object) argument")

        entry = Scope.declare_cfunction(self, name, type, pos, *args, **kwargs)
        entry.is_cproperty = True
        return entry

    def declare_pyfunction(self, name, pos, allow_redefine=False):
        # Add an entry for a method.
        signature = get_property_accessor_signature(name)
        if signature:
            entry = self.declare(name, name, py_object_type, pos, 'private')
            entry.is_special = 1
            entry.signature = signature
            return entry
        else:
            error(pos, "Only __get__, __set__ and __del__ methods allowed "
                "in a property declaration")
            return None


class CConstOrVolatileScope(Scope):

    def __init__(self, base_type_scope, is_const=0, is_volatile=0):
        Scope.__init__(
            self,
            'cv_' + base_type_scope.name,
            base_type_scope.outer_scope,
            base_type_scope.parent_scope)
        self.base_type_scope = base_type_scope
        self.is_const = is_const
        self.is_volatile = is_volatile

    def lookup_here(self, name):
        entry = self.base_type_scope.lookup_here(name)
        if entry is not None:
            entry = copy.copy(entry)
            entry.type = PyrexTypes.c_const_or_volatile_type(
                    entry.type, self.is_const, self.is_volatile)
            return entry


class TemplateScope(Scope):
    def __init__(self, name, outer_scope):
        Scope.__init__(self, name, outer_scope, None)
        self.directives = outer_scope.directives
